Answer:
• (a)900 test scores
,
• (b)1350 test scores
Step-by-step explanation:
Part A
First, determine the number of test scores below Q2
![\begin{gathered} 50\%\text{ of }1800=(50)/(100)*1800 \\ =(1)/(2)*1800 \\ =900 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/l2zgdmw8kovclf4zir5142hnn1no574s5i.png)
If a sample consists of 1800 test scores, 900 of them would be at or below the second quartile (Q2).
Part B
Next, determine the number of test scores above Q1.
Since 25% of the test scores are below Q1, 75% of the test scores will be above Q1.
![\begin{gathered} 75\%\text{ of }1800=(75)/(100)*1800 \\ =(3)/(4)*1800 \\ =1350 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/sy72x173g8fss5ei4xrz8m9k3zisgk8wum.png)
If a sample consists of 1800 test scores, 1350 of them would be at or above the first quartile (Q1).