The following data are from a simple random sample : 1, 4, 7

The point estimate of the population standard deviation is :

3

The correct answer is Option (4) → 3

The sample standard deviation is,

$s=\sqrt{\frac{∑(x_i-\bar x)^2}{n-1}}$

Now,

Sample Mean $\bar x=\frac{1+4+7}{3}=\frac{12}{3}=4$

$∴s=\sqrt{\frac{(1-4)^2+(4-4)^2+(7-4)^2}{3-1}}=\sqrt{\frac{18}{2}}=3$