Question

What is the average of all integers between 300 and 450 that are exactly divisible by 13?

• A. 277
• B. 377
• C. 477
• D. 577

Answer 1

Answer:

B. 377

The numbers divisible by (13) between (300) and (450) form an AP.

First divisible number:

$13 \times 24 = 312$

Last divisible number:

$13 \times 34 = 442$

For an arithmetic progression, the average is:

$\frac{\text{first term}+\text{last term}}{2}$

$= \frac{312+442}{2}$

$= \frac{754}{2}$

$= 377$

Therefore, the average is:

$\boxed{377}$