What is the difference between the sixth and the fifth terms of the sequence...

[BTGmoderatorLU]

Source: GMAT Paper Tests

What is the difference between the sixth and the fifth terms of the sequence 2, 4, 7,. . . whose nth term is n+2^(n-1)?

A. 2
B. 3
C. 6
D. 16
E. 17

The OA is E

[Scott@TargetTestPrep]

Source: GMAT Paper Tests

What is the difference between the sixth and the fifth terms of the sequence 2, 4, 7,. . . whose nth term is n+2^(n-1)?

A. 2
B. 3
C. 6
D. 16
E. 17

The OA is E

Solution:
To find the sixth term, let's first substitute 6 for n.
6 + 2^(6-1)6 + 2^5
6 + 32 = 38
To find the fifth term, we substitute 5 for n.
5 + 2^(5-1)
5 + 2^4
5 + 16 = 21
The difference between the 6th and 5th terms of the sequence is 38 – 21 = 17.
Answer: E