The amount of Jens 11 What is the probability that her next

The amount of Jen\'s $11. What is the probability that her next phone bill will be more than $507 monthly phone bill is normally distributed with a mean of $54 and a standard deviation of ANSWER: 2. Mary randomly selected 320 light bulbis and tested them in a laboratory, the found that 245 lasted more than 500 87% confidence interval to estimate the proportion of all light bulbs that last more than 500 hours. hours. Find the (Round final answer to 3 significant digits) Answer. Confidence Interval L Interpretation (in detailed non-technical words)

Solution

Answer:

Mean is 54 and SD is 11 . z is calculated as (x-mean)/SD

We need to find P(x>50) =P(z>(50-54)/11)=P(z>-0.36) or P(z<0.36)

From normal distribution table we get 0.6406 (look at the right most column for 0.3 and the top most row for 0.06)