Can someone help me understand how to approach this equation please... The scores on an economics examination are normally distributed with a mean of 73 and a standard deviation of 16. If the instructor assigns a grade of A to 14% of the class, what is the lowest score a student may have and still obtain an A?

Question

kropot72 · Answer

Can you use a standard normal distribution table to find the z-score for a cumulative probability of 1.00 - 0.14 = 0.86?

kropot72 · Answer

@pbzdusek Are you sure that you have copied the question correctly? With the parameters that are given, the distribution of the scores cannot be normal.

anonymous · Answer

yes i copied it correctly.  that is my problem... to me it doesn't make sense

kropot72 · Answer

To make the question valid, the maximum score needs to be greater than 100. In that case the question is correct because the distribution of the scores can then be normal.
Do you have a standard normal distribution table?

anonymous · Answer

yes

kropot72 · Answer

Try to use your table 'in reverse' to find the value of z that gives a cumulative probability of 0.8599.

anonymous · Answer

ok... got it... thanks

kropot72 · Answer

You're welcome :)