Sarah is doing research on the average age of first-year resident physicians. She wants her estimate to be accurate to within 1 year. From past studies, she knows the population standard deviation is 8.265. How many first-year residents must she survey to be 95% confident?

The number of first-year residents she must survey to be 95% confident= 263

Step-by-step explanation:

When population standard deviation ()  is known and margin of error(E) is given, then the minimum sample size (n) is given by :-

, z* = Two-tailed critical value for the given confidence interval.

For 95% confidence level , z* = 1.96

As, = 8.265, E = 1

So,

Hence, the number of first-year residents she must survey to be 95% confident= 263

need more information

step-by-step explanation:

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.