Directions: Identify the number that correctly fills the blank in the series.

215, 222, 229, 236, 243, ?, 257

The correct answer is 250.

Step-by-step Explanation:

To find the number that correctly fills the blank in the given series, we need to examine the difference between consecutive terms:

$222-215=7$

$229-222=7$

$236-229=7$

$243-236=7$

Notice that each number in the sequence increases by a constant value of 7 (it is an arithmetic progression with a common difference of 7).

To find the missing term, add 7 to the preceding number (243):

$243+7=250$

We can verify our answer by adding 7 to 250 to see if it gives the final term in the series:

$250+7=257$

Since 257 matches the given final term, the number that correctly fills the blank is 250.