Explanation:
We know that
14^2=196, and
15^2=225
so we know that sqrt(215) is between 14 and 15.
How do we know if it is between 14.5 and 15?
we need to know the value of 14.5^2, which we can calculate in the head as follows:
The square of all numbers ending in 5 such as 15 can be calculated by breaking up the 5 and the preceding digit(s),
The preceding digit is 1. We multiply 1 by the next integer, 2 to get 2.
Attach 25 to 2 gives us 225 (as we saw above.
Example, 145*145 = 14*15 | 25 = 210 | 25 = 21025
so
14.5^2 = 210.25, which gives the more precise answer that
14.5^2 < 215 < 15^2, or
14.5 < sqrt(215) < 15 (fourth choice)
Since the third choice says sqrt(215) is between 14 and 1.5 (not 15), so the third choice is incorrect.
Note: if we eliminated the third choice, i.e. discard the likelihood of typo in the question, the only one left is the fourth choice.