:1. Solution.  Since (420-500)/100 = -80/100 = -.8 and     
(525-500)/100 = 25/100 = .25, the percentage scoring between 420
and 525 is equal to the area under the normal curve between  -.8
and .25.  The area between  -.8 and 0 is about 58/2 = 29%, and
the area between 0 and .25 is about 20/10 = 10%.  So the answer
is  29% + 10% = 39%, which is closest to 40%.