Consider the following hypothesis test :

$H_0 : \mu ≤20$

$H_a : \mu > 20 $

A sample of 49 provided a sample mean of 19.40. The population standard deviation is 2. The value of the test statistic is :

-2.1

The correct answer is Option (2) → -2.1

The z-score formula,

$z=\frac{\bar x-μ_0}{σ/\sqrt{n}}$

$=\frac{19.40-20}{2/\sqrt{49}}=\frac{-0.60}{0.2857}$

$≃-2.1$