Question: The average of first four prime numbers greater than 20 is?
Options:
(A) 10
(B) 20
(C) 30
(D) 40
(E) 50
Answer: 23 + 29 + 31 + 37 = 120/4 = 30
The answer is (C).

Question: If x is a positive odd integer and y is a negative even integer, which of the following must be true?
Options:
(A) x^3 + y is a positive odd integer
(B) x^2 + y^2 is a negative odd integer
(C) x^0 + y^11 is a negative odd integer
(D) x + y is a positive odd integer
(E) x + y is a negative odd integer
Answer: Anything power 0 is always 1 and given that Y is even and negative, then
1 + (-2) will be negative with odd power values for Y.
The answer is (C).

Question: There are seven thieves. They stole diamonds from a diamond merchant and ran away. While running, night sets in and they decide to rest in the jungle.
When everybody was sleeping, two of them woke up and decided to divide the diamonds equally among themselves. But when they divided the diamonds equally, one diamond is left.
So they woke up the 3rd thief and tried to divide the diamonds equally again but still one diamond was left. Then they woke up the 4th thief to divide the diamonds equally again, and again one diamond was left. This happened with the 5th and 6th thief – one diamond was still left.
Finally, they woke up the 7th thief and this time the diamonds were divided equally.
How many diamonds did they steal in total?
Options:
(A) 2397
(B) 2401
(C) 2411
(D) 2423
(E) None of the above
Answer: We need a number that is a multiple of 7 that will give a remainder of 1 when divided by 2, 3, 4, 5, and 6. The least common multiple of these numbers is 60. So, we need a multiple of 7 that is 1 greater than a multiple of 60.
The answer is (B).

Question: Three years ago, the average age of a family of 5 members was 17. A baby having been born, the average age of the family is the same today. What is the age of the child?
Options:
(A) 3
(B) 2
(C) 4
(D) 1
(E) 5
Answer:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Present age of 5 members = 5 x 17 + 3 x 5 = 100 years
Also, present ages of 5 members + Age of the baby = 6 x 17 = 102 years
Age of the baby = 102 – 100 = 2 years.
The answer is (B).