10 second questions

Jai Ganesh · 2008-05-15 21:22:43

#643. Complete the series:

3, 4, 6, 8, 12, 14, 18, 20, ____.

#644. What is the area of the biggest square that can be inscribed in a circle of area (pi/2) square units?

Jai Ganesh · 2008-05-16 17:23:27

#645. If a number is written as 2F7 in Hexadecimal, what is the number in decimal?

#646. There are 16 bottles in a crate. The crates are arranged in the form of a cuboid with length 16 crates, width 16 crates and height 16 crates. How many bottles are there in all?

JohnnyReinB · 2008-05-16 22:43:13

Jai Ganesh · 2008-05-16 23:11:07

Answers to 635, 636, 637, 641, 642, 645, and 646:-
Outstanding performance, JohnnyReinB!
All the answers other than the one to #636 are correct.
I concede I shouldn't have posted problem #636 here.

#647. A 20 digit binary number is made up of all 1s. What is the number in decimal?

#648. A book contains 2400 pages with page numbers printed from 1 to 2400. How many numbers have been printed in all in the page numbers (that is, the total number of digits printed)?

Jai Ganesh · 2008-05-16 23:26:36

#649. The smallest perfect number is 6, followed by 28. Which is the next perfect number?
(A perfect number is one whose factors add up to the number itself).

#650. Which is the smallest 'Abundant' or 'Excessive' nu8mber in the realm of counting numbers?
(An abundant number is one whose sum of factors is greater than the number).

Jai Ganesh · 2008-05-17 02:12:02

#651. A sells a motor car at a gain of 20% of his cost price to B. B sells the motor car to C at a gain of 20%. C sells the car to D at a gain of 20%. If the car cost $300 to A, what price did D sell the car?

#652. Complete the series:-

1, 32, 243, 1024, 3125, _____

#653. How many degress aprroximately is a radian?

JohnnyReinB · 2008-05-17 15:13:59

I keep on forgetting the volume of a sphere. I squared the radius, hehe.

Last edited by JohnnyReinB (2008-05-17 15:15:02)

Jai Ganesh · 2008-05-17 22:15:59

Answers to #647 and #650:

647:- The answer you have posted is absolutely right, JohnnyReinB. Well done.

650:- Your answer isn't correct, JohnnyReinB. All prime numbers, their squares and higher powers are Deficient numbers. That is, the sum of the factors would always be less than the number itself.
For example, the factors of 81 are1, 3, 9, and 27. They add up to 40 only, which is much lesser than 81. Therefore, 81 is a deficient number.

Try again.

#654. Make a list of all the distinct prime factors of the number 528.

#655. What is the Least Common Multiple of 26, 28, and 36?

#656. How many numbers between 1 and 1,000,000 (both the numbers included) are perfect fourth powers of Natural numbers?

Jai Ganesh · 2008-05-17 22:58:44

#657. How many feet per second is a speed of 36 miles per hour?

#658. Complete the series:
2, 3, 7, 25, 121, 721, ___.

#659. What is the angular velocity in radians/second of the minute hand of a clock?
(a) Between 0 and 0.1
(b) Between 0.1 and 0.2
(c) Between 0.2 and 0.3
(d) Between 0.3 and 0.4

#660. A tightly packed container of dimensions 100 cms x 100 cms x 100 cms is filled with solid lead cylinders of diameter 10 cms and height 10 cms. What portion (volume) of the container is not filled with lead cylinders?

JaneFairfax · 2008-05-18 04:41:46

Last edited by JaneFairfax (2008-05-18 04:42:28)

Jai Ganesh · 2008-05-18 19:15:13

Answer to #655:-
You are correct, JaneFairfax! Very good!

#661. What is the difference between the square of the highest prime number between 20 and 30 and the square of the lowest prime number between 20 and 30?

JohnnyReinB · 2008-05-18 22:09:00

oops. hehe.

Jai Ganesh · 2008-05-18 22:20:53

Answers to #650, #654 and #661:
All correct, JohnnyReinB!

#662. What is the value of

?

#663. What is the value of

approximately?

JaneFairfax · 2008-05-18 22:46:21

Jai Ganesh · 2008-05-19 01:46:14

Answer to #662 :
Absolutely right, JaneFairfax! Good work!

#663. A, B, C, and D go shopping. A buys a shirt for a certain price. B buys a shirt which is 10% costlier than that of A. C buys a shirt costing 10% more than that os B. D buys a shirt costing 10% more than that of C. If the total expenditure incurred is $4641, how much did A's shirt cost him?

#664. If

, then

#665. Which of the following is false?
(a) For x>1, x! is always even.
(b) For x>1, √x >1.
(c) Every prime number can be expressed as 6n-1 or 6n+1.
(d) There are more than 240 numbers between 1 and 1000 which are divisible by 4.
(e) There are more than 200 numbers between 1 and 1000 which are divisible by 6.
(f) The list of Pythagorean triples is infinite.

Jai Ganesh · 2008-05-19 02:26:50

#666. Successive discounts of 50%, 25% and 20% on a purchase is equal to a single discount of _____ percent.

#667. If a 100 meter long train crosses a 200 meter long bridge in 30 seconds, what is the speed of the train in kilometers/hour?

#668. What is the value of

approximately?

#669. An even number leaves a remainder of 1 when divided by 1001. What would the remainder be when the number is divided by 14?

Jai Ganesh · 2008-05-19 21:14:37

#670. Two trains are moving in opposite directions at speeds of 60 km/hour and 90 km/hour. Their lengths are 1.10 km and 0.9 km respectively. What is the time taken by the slower train to cross the faster train in seconds?

#671. Find the whole number which when increased by 20 is equal to 69 times the reciprocal of the number.

#672. A fathers age is three times the sum of the ages of his two children, but 20 years hence his age will be equal to the sum of their ages. What is the father's present age?

#673. A circular road runs around a circular garden. If the difference between the circumference of the outer circle and the inner circle is 44 m, then what is the width of the road?

JaneFairfax · 2008-05-19 22:52:14

Jai Ganesh · 2008-05-19 23:25:15

Answer to #665:
You are correct, JaneFairfax! Good work!

#674. The number 311311311311311311311 is:
(a) divisible by 3 but not by 11
(b) divisible by 11 but not by 3
(c) divisible by both 3 and 11
(d) neither divisible by 3 nor by 11

#675. The average of nine numbers is M and the average of
three of these is P. If the average of remaining numbers is N, then:
(a) M = N + P
(b) 2M = N + P
(c) 3M = 2N + P
(d) 3M = 2P + N

JaneFairfax · 2008-05-19 23:53:08

Jai Ganesh · 2008-05-20 02:52:20

Answers to #669 and #675 :
Both correct, JaneFairfax!

#676. What is the value of

when a=26?

#677. What is the value of
5³+6³+7³+8³+9³+10³?

#678. {3,5,7} are the only triplet primes in the world of numbers. How would you prove this in the simplest way?

TheDude · 2008-05-20 03:13:20

JaneFairfax · 2008-05-20 03:25:05

Jai Ganesh · 2008-05-20 18:34:20

Answers to #663, #664, #666, #667, #670, #671, #672, #673, #674, and #678.

All correct, TheDude!

Good reasoning, JaneFairfax! Well done!

#679. The circumference of a circle is equal to the
perimeter of a square whose area is 121 sq cms. What is the area of the circle?

#680. A boat covers a distance of 24 kms in 10 hours
downstream. To cover the same distance upstream, the boat takes two hours longer. What is the speed of the boat in still waters?

#681. Sonia started a business by investing $60,000. Six months later, Mike joined her by investing $140,000. After one year, Ben joined them by investing $120,000. At the end of two years from the commencement of business, they earn a profit of $450,000. What is Mike's share of the profit?

#682. On childrens day chocolates were to be equally
distributed amongst 540 children. But on that particular day, 120 children were absent. Thus, each child got 4 chocolates extra. How many chocolates was each child originally supposed to get?

#683. What is the value of x if

?

Jai Ganesh · 2008-05-20 21:28:28

#684. A clock showed a time of fourteen minutes past nine (9 hours and 14 minutes). The positions of the hour-hand and the ninute-hand of the clock are exactly interchanged. What is the new time shown by the clock closest to?

#685. 3 single-digit numbers are chosen at random from 1, 2, 3, 4, 5, 6, 7,8 and 9 without repeating any digit. What is the probability that their product is odd?

#686. In a question paper, there are four multiple-choice questions. Each question has five choices with only one choice as its correct answer. What is the total number of ways in which a candidate would not get all the four answers correct?

Math Is Fun Forum

#601 2008-05-15 21:22:43

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