Answer
$t_0\lt t_α$: null hypothesis is not rejected.
There is not enough evidence that the children have higher IQs.
Work Step by Step
$H_0:~µ=100$ versus $H_1:~µ\gt100$
Requirement:
The population from which the sample is extracted is normally distributed.
$n=20$, so:
$d.f.=n-1=19$
$t_0=\frac{x ̅-µ_0}{\frac{s}{\sqrt n}}=\frac{104.2-100}{\frac{14.7}{\sqrt {20}}}=1.278$
$t_α=t_{0.05}=1.729$
(According to Table VI, for d.f. = 19 and area in right tail = 0.05)
Since $t_0\lt t_α$, we do not reject the null hypothesis.
