Answer
a)92.87%
b)95.2%
c)Yes.
Work Step by Step
a)$z=\frac{value-mean}{standard \ deviation}=\frac{20-24}{2.6}=-1.54.$
$z=\frac{value-mean}{standard \ deviation}=\frac{30-24}{2.6}=2.31.$
By using the table the corresponding probability: 0.9896-0.0618=0.9287=92.87%.
b)$z=\frac{value-mean}{standard \ deviation}=\frac{19.5-24}{2.6}=-1.73.$
$z=\frac{value-mean}{standard \ deviation}=\frac{30.5-24}{2.6}=2.5.$
By using the table the corresponding probability: 0.9938-0.0418=0.952=95.2%.
c) Yes it does because the difference between the result of a) and b) is more than 2%.
