Browsing as Guest. Progress, bookmarks and attempts are disabled.
Log in to track your work.
June 2006 p6 q7
3342
A survey of adults in a certain large town found that 76% of people wore a watch on their left wrist, 15% wore a watch on their right wrist and 9% did not wear a watch.
A random sample of 200 adults was taken. Using a suitable approximation, find the probability that more than 155 wore a watch on their left wrist.
Solution
Let the random variable \(X\) represent the number of adults wearing a watch on their left wrist. Given that 76% wear a watch on their left wrist, \(X\) follows a binomial distribution \(B(n=200, p=0.76)\).
We approximate this binomial distribution with a normal distribution. The mean \(\mu\) and variance \(\sigma^2\) are calculated as follows: