A psychologist has been studying eye fatigue using a particular measure,
which she administers to students after they have worked for 1 hour writing on
a computer. On this measure, she has found that the distribution follows a
normal curve. The test of eye fatigue has a mean of 15 and a standard deviation
of 5. Using a normal curve table, what score on the eye fatigue measure would a
person need to have to be in the top 40%?

On the table you have to find what z-score has a 0.60 area meaning its in the top 40% because 60% of the curve is below it. This is going to give a z-score of about .26 (the area for this is 0.6026). The formula for z-score is (value-mean)/standard deviation. z=(v-m)/s We can rearrange this to zs=v-m then zs+m = v

Plugging in values we get zs+m=v, (0.26)(5)+15=16.3

If you want want a calculator would tell you I can redo the math because it will have a more accurate z-score.

Don't be afraid to ask me any more questions. Please ask me for clarification before you withdraw.

Oct 13th, 2015

Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.