A member is designing a study to standardize new intelligence test. It is known that scores on this type of test are normally distributed with a standard deviation of 15.0

1. Write down in terms of x the sample mean and n, the sample size, an expression for a 99% symmetric confidence interval for the mean of test score.
2. Calculate, to the nearest hundred, the value of n such that the with of this confidence intervalwill be less than 10