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Select the correct answer.

Raw scores on a certain standardized test one year were normally distributed, with a mean of 156 and a standard deviation of 23. If 48,592 students took the test, about how many of the students scored less than 96?

\begin{tabular}{|c|c|c|c|c|c|c|c|c|}
\hline
\multicolumn{8}{|c|}{Table shows values to the LEFT of the z-score} \\
\hline [tex]$z$[/tex] & 0.00 & 0.01 & 0.02 & 0.03 & 0.04 & 0.05 & 0.06 & 0.07 \\
\hline 2.5 & 0.99379 & 0.99396 & 0.99413 & 0.99430 & 0.99446 & 0.99461 & 0.99477 & 0.99492 \\
\hline 2.6 & 0.99534 & 0.99547 & 0.99560 & 0.99573 & 0.99585 & 0.99598 & 0.99609 & 0.99621 \\
\hline 2.7 & 0.99653 & 0.99664 & 0.99674 & 0.99683 & 0.99693 & 0.99702 & 0.99711 & 0.99720 \\
\hline 2.8 & 0.99744 & 0.99752 & 0.99760 & 0.99767 & 0.99774 & 0.99781 & 0.99788 & 0.99795 \\
\hline 2.9 & 0.99813 & 0.99819 & 0.99825 & 0.99831 & 0.99836 & 0.99841 & 0.99846 & 0.99851 \\
\hline -2.9 & 0.00187 & 0.00181 & 0.00175 & 0.00169 & 0.00164 & 0.00159 & 0.00154 & 0.00149 \\
\hline -2.8 & 0.00256 & 0.00248 & 0.00240 & 0.00233 & 0.00226 & 0.00219 & 0.00212 & 0.00205 \\
\hline -2.7 & 0.00347 & 0.00336 & 0.00326 & 0.00317 & 0.00307 & 0.00298 & 0.00289 & 0.00280 \\
\hline -2.6 & 0.00466 & 0.00453 & 0.00440 & 0.00427 & 0.00415 & 0.00402 & 0.00391 & 0.00379 \\
\hline -2.5 & 0.00621 & 0.00604 & 0.00587 & 0.00570 & 0.00554 & 0.00539 & 0.00523 & 0.00508 \\
\hline
\end{tabular}

A. 220

B. 18,627

C. 60

D. 19,312


Sagot :

To find the number of students who scored less than 96 on the standardized test, we need to follow a detailed, step-by-step process. Let's walk through the solution:

1. Identify the given values:
- Mean ([tex]\(\mu\)[/tex]) = 156
- Standard deviation ([tex]\(\sigma\)[/tex]) = 23
- Total number of students ([tex]\(N\)[/tex]) = 48,592
- Score ([tex]\(X\)[/tex]) = 96

2. Calculate the z-score:
The z-score formula is:
[tex]\[ z = \frac{X - \mu}{\sigma} \][/tex]
Substituting the provided values:
[tex]\[ z = \frac{96 - 156}{23} = \frac{-60}{23} \approx -2.6087 \][/tex]

3. Find the cumulative probability corresponding to the calculated z-score:
Use the z-table to find the cumulative probability for [tex]\(z \approx -2.6\)[/tex].

Looking at the provided z-table, we see:
- For [tex]\(z = -2.6\)[/tex], the cumulative probability is approximately 0.004.
- For [tex]\(z = -2.7\)[/tex], the cumulative probability is approximately 0.00347.

Interpolating, the cumulative probability for [tex]\(z \approx -2.6087\)[/tex] is approximately 0.00187.

4. Calculate the number of students who scored less than 96:
Multiply the total number of students by the cumulative probability.
[tex]\[ \text{Number of students} = N \times \text{cumulative probability} \][/tex]
Substituting in the values:
[tex]\[ \text{Number of students} = 48,592 \times 0.00187 \approx 90.86704 \][/tex]

5. Select the correct answer:
Given the options and the calculated number of students (approximately 90.86704), the closest answer is:

C. 60