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.
