Answer to Question #332260 in Statistics and Probability for yvonne

Question #332260

A teacher realizes that his students' marks on a statistic test are normally distributed with a mean of 62 and a standard deviation of 15. If the teacher wishes to assign minimum marks for grade B is referring to the top 30 per cent of the students' marks in the class, how many marks are required to get a minimum mark for grade B?


1
Expert's answer
2022-04-25T08:20:04-0400

μ=62,σ=15.\mu=62, \sigma=15.

The 70th percentile of a normal distribution is z=0.524 (find from z-table);z=0.524\text{ (find from z-table)};

P(Z<0.524)=0.7;P(Z>0.524)=10.7=0.3;z=xμσ;P(Z<0.524)=0.7;\\ P(Z>0.524)=1-0.7=0.3;\\ z=\cfrac{x-\mu}{\sigma};\\

x=zσ+μ=0.52415+62=69.86.x=z\sigma+\mu=0.524\cdot15+62=69.86.

If marks are integers, than the minimum mark for grade B is 70.


Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!

Comments

No comments. Be the first!

Leave a comment