​Claim: The standard deviation of pulse rates of adult males is less than 12 bpm. For a random sample of 155 adult​ males, the pulse rates have a standard deviation of 10.8 bpm. Complete parts​ (a)...

​Claim: The standard deviation of pulse rates of adult males is less than 12
bpm. For a random sample of 155 adult​ males, the pulse rates have a standard deviation of 10.8 bpm. Complete parts​ (a) and​ (b) below.