we will use the following formula to find the Z value
[tex]Z=\frac{x-\mu}{\frac{\sigma}{\sqrt[]{n}}}[/tex]
where,
x : sample mean = 26.7
μ : mean of expectation = 27.99
σ : standard deviation = 4.02, and
n : sample = 45
therefore:
[tex]Z=\frac{x-\mu}{\frac{\sigma}{\sqrt[]{n}}}=\frac{26.7-27.99}{\frac{4.02}{\sqrt[]{45}}}[/tex]
solving this, we obtain:
-2.15263...
rounded to 2 decimal places
-2.15
