ni=2(ZσE)2=2(1.96(17.1)3)2=249.6

Description:

Math equation. "n" sub i equals 2 times the square of the quantity Z times standard deviation divided by E, the margin of error. In this case, n equals 2 time the square of 1.96 times 17.1 divided by 3. The final answer is 249.6.