Consider the following hypothesis test:-
$H_0: μ = 20$
$Η_a: μ ≠20$
A sample of 40 provided a sample mean of 19. The standard deviation is 3. Then the value of the t-test statistic is:

-2.1

The correct answer is Option (2) → -2.1 **

Given:

$H_0:\mu=20$

Sample mean $\bar{x}=19$

Sample size $n=40$

Standard deviation $s=3$

Test statistic:

$\displaystyle t=\frac{\bar{x}-\mu_0}{s/\sqrt{n}}$

Substitute:

$t=\frac{19-20}{3/\sqrt{40}}$

$t=\frac{-1}{0.4743}\approx -2.108$

t ≈ -2.11