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#1 2017-07-17 18:16:20

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

percentage

Q1. If x percent of y is 50 then what is y
a.     2x
b.      50x
c.       x
d.     NOne

Q2...   in july,the prize of sugar increased by 10% , in August,it is declined by 20% and in september,it is increased by 10%,What is final Decline in prize
a.3.2%
b.Zero
3.20%
c...None


MZk

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#2 2017-07-17 19:03:20

bob bundy
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Registered: 2010-06-20
Posts: 8,170

Re: percentage

hi Zeeshan 01

Q1.  Solve this for y:

Q2.  The best way to solve this is to change the percents into 'multipliers'

eg .  An increase of 10% is the same as multiplying the original by 1.1
and a decrease of 20% is the same as multiplying by 0.8

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#3 2017-07-17 21:07:08

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

Re: percentage

Y is 2 time x


MZk

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#4 2017-07-17 21:08:11

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

Re: percentage

eg .  An increase of 10% is the same as multiplying the original by 1.1
and a decrease of 20% is the same as multiplying by 0.8
Means???


MZk

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#5 2017-07-17 23:02:34

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

Re: percentage

Check question 1 I don't understand your formula


MZk

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#6 2017-07-17 23:23:11

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

Re: percentage

X percent is x\100


MZk

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#7 2017-07-18 00:05:32

zetafunc
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Registered: 2014-05-21
Posts: 2,131
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Re: percentage

To find
of
, you'd do:

Similarly, to find
of
, you'd do:

We're given that that is
, so that means

i.e.

Zeeshan 01 wrote:

eg .  An increase of 10% is the same as multiplying the original by 1.1
and a decrease of 20% is the same as multiplying by 0.8
Means???

If you wanted to increase 20 by 10%, one way of doing that is just to do
That's because

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#8 2017-07-18 00:13:59

bob bundy
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Registered: 2010-06-20
Posts: 8,170

Re: percentage

Zeeshan 01 wrote:

Y is 2 time x

Correct!

Multipliers

example.  Increase $20 by 15%

so

The last calculation here is the quickest way to get the new value.

To write a multiplier

(1) Write the % as a decimal (0.15)
(2) Add 1 (1.15)

If there is a percentage decrease:

example. Decrease $20 by 15%

so

To write the multiplier for a decrease

(1) Write the % as a decimal (0.15)
(2) Subtract from 1 (0.85)

If there are 3 percentages changes:

(1) Work out the 3 multipliers and times them together (M = M1 x M2 x M3)

(2) Convert back to a single % (M-1)/100

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#9 2017-07-18 04:01:33

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

Re: percentage

He is saying that y =5000\x????


MZk

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#10 2017-07-18 04:04:13

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

Re: percentage

Is it true??


MZk

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#11 2017-07-18 15:36:31

Monox D. I-Fly
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Registered: 2015-12-02
Posts: 952

Re: percentage

yes

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#12 2017-07-18 19:17:34

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

Re: percentage

so why ans is 2x


MZk

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#13 2017-07-18 19:27:18

Zeeshan 01
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Registered: 2016-07-22
Posts: 648

Re: percentage

we dont know value of x


MZk

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#14 2017-07-18 19:51:14

bob bundy
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Registered: 2010-06-20
Posts: 8,170

Re: percentage

If x percent of y is 50

I think the confusion is because of the wording here.  I assumed this meant x is 50% of y, which leads to y = 2x as an answer.

zetafunc assumed this meant x% of y is 50., which leads to his answer.  That is a correct interpretation of what is written, but this wording is not how a person brought up on maths In England would phrase the question **. I noticed the multi-choice possibilities and decided to interpret the wording accordingly.

On a world-wide forum, where most posters communicate in English, this is going to happen occasionally.  We all just have to be aware of the difficulty and make allowances. 

Bob

** If I was setting this as a question I would write "x is a fraction of y.  When written as a percentage, it is 50%.   What is y in terms of x?"


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#15 2017-07-19 00:15:28

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 648

Re: percentage

Bob wrote:

I assumed this meant x is 50% of y,

That is not given in my question


MZk

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#16 2017-07-19 19:02:13

bob bundy
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Registered: 2010-06-20
Posts: 8,170

Re: percentage

Ok.  In that case zetafunc's answer is correct.

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#17 2017-07-19 23:08:26

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 648

Re: percentage

So question 1 ans is D? ?


MZk

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#18 2017-07-20 01:08:05

bob bundy
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Registered: 2010-06-20
Posts: 8,170

Re: percentage

It would appear so.  dizzy

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#19 2017-07-20 02:07:29

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 648

Re: percentage

Uff!!!


MZk

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#20 2017-07-20 02:08:32

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 648

Re: percentage

If we know x then the value of y is determined!!!! In question 1


MZk

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#21 2017-07-20 03:53:52

bob bundy
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Registered: 2010-06-20
Posts: 8,170

Re: percentage

Yes.  See post 7.

B


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#22 2017-07-20 12:36:40

sonia100
Member
Registered: 2017-07-20
Posts: 2

Re: percentage

Q2...   in july,the prize of sugar increased by 10% , in August,it is declined by 20% and in september,it is increased by 10%,What is final Decline in prize
a.3.2%
b.Zero
3.20%
c...None

The answer is "a"

Explanation:
First let's assume this is the price for a 30 pound bag of sugar, which we will just call a bag. 

Say the price of a bag, in June was $100.00. Come July and the price goes up 10%. Ten percent of 100.00 means 10 per 100; or ten out of every hundred things.  Ten cents out of one hundred cents, is 10 cents out of a dollar so 10 cents is ten per cent of a dollar.  Just like ten dollars are ten percent of a one hundred dollars bill.
So you add 10% of $100.00, to $100.00 you get ...
   
          $100.00  + $10.00 = $110.00   

$110.00  becomes the new price for the same bag of sugar, after the July increase.

To obtain the new price,  you need to find out what 10% of the price is.
remember 10 cents = 10% of a dollar, if you look at the display at the store, there is a decimal point, and after the decimal point the cents are shown. 10 cents are shown as $ .10

To get 10% of any number, just multiply the number times 0.10
To get 20% of any number, just multiply the number times 0.20
To get 25% of any number, just multiply the number times 0.25

To obtain the new price you multiplied 100 x 10% = 10.00. Then added the result to the $100.00

But in August, the price goes down by 20%. That is 20 cents out of every dollar.  So now you have to deduct, which means subtract, 20%f of the new price. If your bag during July sold for $110.00, after the August decrease, the same bag, will sell for 20% less.

Lets find 20% of $110.00  by multiplying $110.00 times 0.20

          110.00 x .20 = 22.00

So the new price in August is:

         $110.00 - $22.00 = $88.00 price after the August reduction in price.

Come September, an increase of 10% of $88.00.

         $ 88.00 x 0,10 =  $8.80

So the new price is:

         $ 88.00 + $8.80 = $96.80 

With this information we can answer the question:

If sugar was $100.00 a bag before any of this, and sugar is now $96.80 per bag,
The price definitely declined, but, by what percentage?

         $100.00 - $96.80 =  $3.20

if it was $100.00 a bag, and it declined by  $3.20 per bag
the decline is 3.2 dollars out of 100 dollars which is answer "a".

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#23 2017-07-20 20:32:56

bob bundy
Administrator
Registered: 2010-06-20
Posts: 8,170

Re: percentage

hi sonia100

Welcome to the forum.

Good explanation!

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#24 2017-07-20 21:02:45

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 648

Re: percentage

Hmm!!!


MZk

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#25 2017-07-20 21:04:32

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 648

Re: percentage

Bob wrote Yes.  See post 7.
B
Means? ?


MZk

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