At a high school, the average grade for the English 10 provincial is 64, with a standard deviation of 10. If 20 students scored between 73 and 86 on the exam, how many students took the exam? Use z scores in your solution

Question

kropot72 · Answer

Can you find the z-score for 73 marks using
$$z=\frac{X-\mu}{\sigma}$$

anonymous · Answer

Excuse me?

kropot72 · Answer

Do you know how to substitute the given values in
$$z=\frac{X-\mu}{\sigma}$$

anonymous · Answer

I believe I do.

kropot72 · Answer

So what z-scores do you get for marks of 73 and 86?

anonymous · Answer

$$z_{ 73}=\frac{73-64}{10}=0.9$$

$$z_{ 86}=\frac{86-64}{10}=2.2$$

kropot72 · Answer

So now it is nenecessary to find the percentage corresponding to the shaded area by referring to the standard normal distribution table with the values found for z
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What percentages do you get for z = 0.9 and z = 2.2 ?