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{9}{|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. 19,312



Answer :

To determine the number of students scoring less than 96 on the standardized test, follow these steps:

1. Calculate the z-score for the score of 96 using the formula:
[tex]\[ z = \frac{X - \mu}{\sigma} \][/tex]
where [tex]\( X \)[/tex] is the score, [tex]\( \mu \)[/tex] is the mean, and [tex]\( \sigma \)[/tex] is the standard deviation.
Given:
[tex]\[ X = 96, \quad \mu = 156, \quad \sigma = 23 \][/tex]
Plugging in the values:
[tex]\[ z = \frac{96 - 156}{23} = \frac{-60}{23} \approx -2.6087 \][/tex]

2. Find the probability corresponding to the z-score of [tex]\(-2.6087\)[/tex] from the standard normal distribution table.
- Locate [tex]\(-2.60\)[/tex] in the row for [tex]\(-2.6\)[/tex].
- Look across the columns to find the closest value for the hundredths place, which is approximately [tex]\(-2.61\)[/tex].

Based on the standard normal distribution table provided, the probability for a z-score [tex]\(-2.6\)[/tex] is approximately 0.00466.

3. Calculate the number of students scoring less than 96 using the probability:
[tex]\[ \text{Number of students} = \text{Probability} \times \text{Total number of students} \][/tex]
Given:
[tex]\[ \text{Probability} = 0.00466, \quad \text{Total number of students} = 48592 \][/tex]
Plugging in the values:
[tex]\[ \text{Number of students} = 0.00466 \times 48592 \approx 226.43872 \][/tex]

Therefore, approximately 226 students scored less than 96 on the standardized test.