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#376 2015-12-31 14:42:43

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi Relentless and bobbym,

M#170. The radius of a solid sphere is 24 cm. It is melted and drawn into a long wire of uniform cross-section. Find the length of the wire if its radius is 1.2 mm.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#377 2015-12-31 15:01:55

Relentless
Member
Registered: 2015-12-15
Posts: 631

Re: Mensuration

Hi ganesh,
The question M#169 originally stated that the base area of the cone was 12 (I assume square centimetres), not the radius.

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#378 2015-12-31 16:52:00

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#379 2015-12-31 17:24:01

Relentless
Member
Registered: 2015-12-15
Posts: 631

Re: Mensuration

Hi bobbym smile
I noticed that you used the same formula, but taking pi to be 22/7
Happy New Year!

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#380 2015-12-31 17:27:37

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi bobbym,

The solution M#170 is perfect! Excellent!

New Year Wishes, bobbym!

M#171. Through a cylindrical pipe, of internal radius 7 cm, water flows out at the rate of 5 cm/second. Calculate the volume of water (in liters) discharged through the pipe in half an hour.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#381 2015-12-31 18:11:49

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;

Hi Relentless;

I always use pi = 22 / 7 when doing these problems.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#382 2016-01-01 00:50:22

Relentless
Member
Registered: 2015-12-15
Posts: 631

Re: Mensuration

Hello! smile

Hey bobbym,
It's a good approximation. For example, for this problem, the error is only about 560mL, or about 725 milliseconds worth of water.
But for some reason, I just don't like using approximations when an exact answer is within reach xS

Last edited by Relentless (2016-01-01 00:54:15)

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#383 2016-01-01 02:46:30

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi bobbym and Relentless,

The solution M#171 is perfect! Brilliant!

M#172. Water in a cylindrical tank of diameter 4 meters and height 10 m is released through a cylindrical pipe of diameter 10 cm at the rate of 2.5 km / hour. How much time will it take to empty the half of the tank? Assume that the tank is full of water to begin with.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#384 2016-01-01 03:16:50

Relentless
Member
Registered: 2015-12-15
Posts: 631

Re: Mensuration

Hello!

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#385 2016-01-01 07:12:10

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#386 2016-01-01 15:43:22

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi Relentless and bobbym,

The solution M#172 is perfect! Excellent, Relentless and bobbym!

M#173. Spherical shaped marbles of diameter 1.4 cm, are dropped into a cylindrical beaker of diameter 7 cm containing some water. Find the number of marbles that should be dropped into the beaker so that the water level rises by 3.6 cm.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#387 2016-01-01 19:18:31

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#388 2016-01-01 20:07:14

Relentless
Member
Registered: 2015-12-15
Posts: 631

Re: Mensuration

Hi!

My answer agrees with yours bobbym, even though it is a strange result for this kind of problem P:

Last edited by Relentless (2016-01-01 20:07:56)

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#389 2016-01-02 00:10:12

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi bobbym and Relentless,

The solution M#173 is perfect! Excellent!

The problem ought to have been:
Spherical shaped marbles of diameter 1.4 cm, are dropped into a cylindrical beaker of diameter 7 cm containing some water. Find the number of marbles that should be dropped into the beaker so that the water level rises by 5.6 cm.

and the solution : 150.

M#174. A cup is in the form of a hemisphere surmounted by a cylinder. The height of the cylindrical portion is 8 cm and the total height of the cup is 11.5 cm. Find the total surface area of the cup.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#390 2016-01-02 06:07:05

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#391 2016-04-01 01:34:27

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi;

M#175. The radii of two circles are 19 cm and 9 cm respectively. Find the radius of the circle which has circumference equal to the sum of the circumferences of the two circles.

M#176. A wheel of a cart is making 4 revolutions per second. If the diameter of the wheel is 84 cm, find the speed of the wheel in centimeters per second.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#392 2016-04-01 15:13:05

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#393 2016-04-01 15:46:12

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi;

The solution M#175 is correct. Well done!

Now, solve M#176, bobbym!


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#394 2016-04-01 15:50:21

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#395 2016-04-01 16:46:14

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi;

The solution M#176 is perfect. Excellent, bobbym!

M#177. The sum of radii of two circles is 140 cm and the difference of their circumferences is 88 cm. Find the diameters of the circles.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#396 2016-04-01 19:01:21

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#397 2016-04-01 23:05:46

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi;

The two solutions in M#177 are correct. Good work, bobbym!

M#178. If the perimeter of a semicircular protractor is 36 cm, find the diameter of the protractor.

.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#398 2016-04-02 00:17:09

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#399 2016-04-02 17:11:12

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,969

Re: Mensuration

Hi;

The solution M#178 is correct. Neat work, bobbym!

M#179. A boy is cycling such that the wheels of the cycle are making 140 revolution per minute. If the diameter of the wheel is 60 cm, calculate the speed per hour at which the boy is cycling.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

Offline

#400 2016-04-03 01:45:32

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Mensuration

Hi;


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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