t test for single mean is given by the formula,

\left|t\right|\ =\ \frac{\overline{x}\ -\ \mu}{\frac{s}{\sqrt{n-1}}}

Where \overline{x} is the sample mean, µ is the population mean, s is the SD and n is the number of observations.

Plugging in \overline{x} = 153.7, \mu = 146.3

s = 17.2, n = 22 in the above formula we get the calculated t value is \frac{153.7\ -\ 146.3}{\frac{17.2}{\sqrt{21}}}\ =\ \frac{7.4}{\frac{17.2}{4.58}}\ =\ \frac{7.4}{3.75}\ \approx1.97

Tabulated Value = 1.72( at 5% level of significance with 21 degrees of freedom) as shown in the table below.

Since the Calculated value > Tabulated value, we reject Ho(Null hypothesis).

I found an answer from opentextbc.ca

Full **Hypothesis Test Examples** – Introductory Business Statistics

Since the **problem** is about a **mean**, this is a **test** of a **single** population **mean**. ... ( Reject the **null hypothesis** when the **null hypothesis** is true.) ... **Step** 3 is the **calculation** of the **test statistic** using the formula we have selected. ... In a **sample** of 16 **sales** calls it **was** found that she closed the contract for an **average** value of 108 ...

For more information, see Full **Hypothesis Test Examples** – Introductory Business Statistics