Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Both #78 and #80 are correct, JaneFairfax!

The questions were posted in a hurry, I didn't have the time to refer my online LaTeX guide. I didn't know it had to be done that way. The inconvenience caused is regretted.

#81. Find the point on the curve

at which the tangent is parallel to the x-axis.#82. Show that the function

is increasing on R.#83. Find the general solution of the differential equation

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Answer to #83:

Correct, JaneFairfax!

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

#84. Prove that the logarithmic function is strictly increasing whenever it is defined.

#85. Find the dimensions and the perimter of a rectangle of area 96 square centimeters whose perimeter is the least.

#86. Find the general solution of the differential equation

#87. The bottom of a cuboidal swimming pool is 25 meters wide and 40 meters long. Water is pumped into the tank at the rate of 500 m³ per hour. Find the rate at which the water level is rising.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Answers to #84, #85, #86, and #87:-

All correct, JaneFairfax!!!

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

#88. The length of the circumference of a circle is equal to the length of the perimter of a triangle of equal sides and also equal to the perimter of a square. Which of the following is true if the areas of the circle, triangle and square are c, t, and s respectively?

(1) s > t > c

(2) c > t > s

(3) c > s > t

(4) s > c > t

#89. In Roman Numerals,

(a) what is the value of MDCCLXXXVII?

(b) what is the value of MCMXCIX?

(c) how is 1995 expressed?

#90. An intelligency agency forms a code of two distinct digits selected from 0, 1, 2, ,3, ....9 such tat the first digit of the code is non-zero. The code, handwritten on a slip, can however create misinterpretation when read upside down - for example, the code 91 may appear as 16. How many codes are there for which no such confusion would arise?

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

#91. If a, a+2, a+4 are prime numbers where

, what is the number of values a can be given?#92. A survey on a sample of 25 new cars being sold at a local automobile dealer was conducted to study which of the three popular facilities - air-conditioning, radio and power windows - were already installed. The survey found

15 had air conditioning;

2 had air conditioning and power windows but no radio;

12 had radio;

6 had air conditioning and radio but no power windows;

11 had power windows;

4 had radio and power windows; and

3 had all the three facilities.

What is the number of cars that had none of these facilities?

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Answer to #91:

Correct, JaneFairfax! **Good!**

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Answer to #89:

Correct, JaneFairfax!!!

Answer to #90:-

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Can you give the list of digits that are potentially confusable, so that we can be sure we are playing the game by the same rules?

*Last edited by JaneFairfax (2009-01-26 02:36:43)*

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Explanation to #90:

Please understand, I'd hate to be unfair and say someone's wrong without enough reason.

What makes you think that 11 or 88 read upside down would cause misinterpretation? They would still appear as 11 and 88 respectively. It was stated in the question '**the code, handwritten in a slip** can however create misinterpretation when read upside down - for example, the code 91 may appear as 16'. Which means 1 is written as |. And

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Then it was entirely my fault. Sorry.

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

#93. The salary of an employee is $1,600. His expenditure on food, clothing, house rent and entermainment are represented by a pie chart making central angles 157.5°, 67.5°, 54°, and 36° respectively. What is his monthly saving?

#94. For any integer n, what is the argument of

#95. In a Geometric Progression, both the first term and the common ratio are

What is the magnitude of the term of the Geometric Progression?

#96. If

, then what is the value of?

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Answers to #95 and #96.

Answer to #95 is correct. **Excellent!!!**

Regarding #96, I guess you've made a minor mistake somewhere. Please try again.

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Answer to #96:-

Correct, JaneFairfax!

#97. If

are the roots of the equation , then what is the value of ?#98. If

, then what is the value of?

#99. If n is an integer other than a multiple of 3, then what is the value of

#100. If n is a multiple of 3, then what is the value of

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

*Last edited by JaneFairfax (2009-01-27 03:28:38)*

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Answer to #97:-

You are correct, JaneFairfax!

#101. If

then, what is the value of ?

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

Answer to #98:

Perfect, JaneFairfax!

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

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 20,922

#102. How many different nine digit numbers can be formed from the number 223355888 by rearranging its digits so that the odd digits occupy even positions?

#103. Five digit numbers are formed using 0, 1, 2, 3, and 4. How many numbers would be there in which atleast one digit is repeated?

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

Offline

**JaneFairfax****Member**- Registered: 2007-02-23
- Posts: 6,868

#103. Can a number start with the digit 0?

Offline