4 In a large population, the systolic blood pressure (SBP) of adults is normally distributed with mean 125.4 and standard deviation 18.6.
- Find the probability that the SBP of a randomly chosen adult is less than 132.
The SBP of 12-year-old children in the same population is normally distributed with mean 117. Of these children 88\% have SBP more than 108. - Find the standard deviation of this distribution.
Three adults are chosen at random from this population. - Find the probability that each of these three adults has SBP within 1.5 standard deviations of the mean.