Question

The weight of a soccer ball is normally distributed with a mean of 0.43 kg and a standard deviation of 0.01 kg.

Answer 1

Mean is 0.43 kg.
0.43+0.1+0.1= 0.45
0.45 is two standard deviation above.
All that are below mean is 50%,
Two standard deviation above is 95%/2=47.5%
50%+47.5% =97.7% are  balls that are less than 0.45 kg.

100%-97.7%=2.5% balls that are more than 0.45 kg

2.3%=0.025

800*0.025 = 20 soccer balls weigh more than 0.45 kg

Answer is b) 20.