please help will rate On the SAT the average Writing score i

please help will rate

On the SAT, the average Writing score is 495 points and the average Mathematics score is 555 points. The standard deviation is 75 points on each part of the test. Now suppose 64 test takers are selected.

4% of the time the sample average Mathematics score should be less than what? (Remember the label.)

Solution

First, we get the z score from the given left tailed area. As          
          
Left tailed area =    0.04      
          
Then, using table or technology,          
          
z =    -1.750686071      
          
As x = u + z * s,          
          
where          
          
u = mean =    555      
z = the critical z score =    -1.750686071      
s = standard deviation =    75      
          
Then          
          
x = critical value =    423.6985447   [ANSWER]