help me please.

A)84.1%

B)97.5%

C)2.5%

Hope this helps!

(a)

Find the z score

[ 20555 - 20500 ] / 55  =  .1

This z score  equates to  .8413  =  84.13% of the days

(b)

Find the z  score

[20610 - 20500] / 55 =  2

This score equates to .9772.....so the % days that the factory  produced  20610 or more skateboards  =

1 - .9772 = .0228  =  2.28%  of the days

(c)

Find the z score

[20445 - 20500 ]  / 55  = -1

This z score equates to .1587 = 15.87%  of the days