How many multiples of 4 lie between 10 and 250?

(Hint: All multiples of 4 form an AP. Find the smallest and largest multiples of 4 between 10 and 250.)

Smallest multiple of 4 greater than 10 = 12

Largest multiple of 4 less than 250 = 248

AP: 12, 16, 20, ..., 248

Here, $a = 12$, $d = 4$, $l = 248$

$$248 = 12 + (n - 1)4$$

$$236 = 4(n - 1)$$

$$n - 1 = 59$$

$$n = 60$$

Therefore, there are 60 multiples of 4 that lie between 10 and 250.