GMAT Practice Question (One of Hundreds)
What is x for the sequence 4, 9 , 25, 49, x, 169, 289, 361?
Correct Answer: A
This is a probability without replacement problem
- The numbers in the sequence are all perfect squares.
- Take the square root of each number in the sequence:
2, 3, 5, 7, square root of x, 13, 17, 19
- These numbers are all primes. The sequence is the list of primes squared
- This means that x is 112 = 121