#1041 - Number Trick Riddle

Sonal asked the class to see if they could find the sum of the first 50 odd numbers. As everyone settled down to their addition, Lavesh ran to her and said, 'The sum is 2,500.' Ms. Sonal thought, 'Lucky guess,' and gave him the task of finding the sum of the first 75 odd numbers. Within 20 seconds, Lavesh was back with the correct answer

How does Lavesh find the sum so quickly and what is the answer ??

View Answer Discuss

The following pattern holds: The sum is equal to n x n, when n is the number of consecutive odd numbers, starting with 1. For example, the sum of the first 3 odd numbers is equal to 3 x 3, or 9; the sum of the first 4 odd numbers is equal to 4 x 4, or 16; the sum of the first 5 odd numbers is equal to 5 x 5, or 25; and so on.

#1042 - Friday The 13th Riddle

Many people would think Friday the 13th will be an unlucky day. Is it possible that there is no Friday on 13th through the whole year? How many Fridays at 13th can we have in a year at most? Can you calculate it out?

View Answer Discuss

We can calculate out how many days there will be for the 13th on each month if we count from the beginning of the year (January 1). Then we divide total days by 7 to get the remainders. We also need to consider the leap year. Through the whole year we had all kinds of remainders, from 0 to 6. The minimum of occurence for all the unique remainders was 1. It means that we have at least one Friday on 13th. In a regular year, the best chance you can get 3 Fridays on 13th, which are in February, March and December because the remainders of these 3 months are 2. In a leap year, the best chance you also can get 3 Fridays on 13th, which are in January, April and July because the remainders of these 3 months are 6.

#1043 - What word am I 1

I am eight letters long - “12345678”
My 1234 is an atmospheric condition.
My 34567 supports a plant.
My 4567 is to appropriate.
My 45 is a friendly thank-you.
My 678 is a man’s name.
Q: What word am I?

View Answer Discuss

MISTAKEN

#1044 - Equation Puzzle

Replace the 'X' by any mathematical symbol to make the expression equal to 99.

18 X 12 X 2 X 3 = 111

View Answer Discuss

18 x 12 ÷ 2 + 3 = 111

#1045 - Mothers Name Humour Puzzle

A cat had three kittens: January,March and May. What was the mother's name.

View Answer Discuss

What
It stated 'WHAT' was the mothers name.

#1046 - Science Puzzle

How can you throw a ball as hard as you can and have it come back to you even if it doesnt hit anything there is nothing attached to it and no one else catches or throws it?

Science Puzzle
View Answer Discuss

Throw the ball straight up in the air.

#1047 - Probability Of Having Same Birthday

How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

View Answer Discuss

Only twenty-three people need be in the room, a surprisingly small number. The probability that there will not be two matching birthdays is then, ignoring leap years, 365x364x363x...x343/365 over 23 which is approximately 0.493. this is less than half, and therefore the probability that a pair occurs is greater than 50-50. With as few as fourteen people in the room the chances are better than 50-50 that a pair will have birthdays on the same day or on consecutive days.

#1048 - Find The Lier Puzzle

A boy and a girl are talking.

"I am a boy" - said the child with black hair.

"I am a girl" - said the child with white hair.

At least one of them lied. Who is the boy and who is the girl?

View Answer Discuss

They both lied.(I said atleast)
(If only one lied they would both be boys or both be girls)

#1049 - Cross The River Puzzle

Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

View Answer Discuss

The boys start on opposite sides of the river

#1050 - Probability Of Second Girl Child

kukki and fukki are a married couple (dont ask me who he is and who she is) :)

They have two kids, one of them is a girl. Assume safely that the probability of each gender is 1/2.
What is the probability that the other kid is also a girl?

Hint: It is not 1/2 as you would first think.

Probability Of Second Girl Child
View Answer Discuss

1/3

This is a famous question in understanding conditional probability, which simply means that given some information you might be able to get a better estimate.

The following are possible combinations of two children that form a sample space in any earthly family:
Girl - GirlGirl - Boy
Boy - Girl
Boy - Boy

Since we know one of the children is a girl, we will drop the Boy-Boy possibility from the sample space.
This leaves only three possibilities, one of which is two girls. Hence the probability is 1/3