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

easy math just plug in a and b

step-by-step explanation:

the correct option is 2.

step-by-step explanation:

according to the given information triangle abc is a right angle triangle with right angle at a. segment ab is 5 and segment ac is 7. point d is on segment bc and angles adb and adc are right angles.

it is given that triangles abd, cad, and cba are similar.

two triangles are similar if their corresponding sides are proportional.

in triangle cba, using pythagoras theorem

                      )

triangle abd and cba are similar,

                            (2)

triangle cad and cba are similar,

                      )

using (1), (2) and (3), we get

hence proved.

therefore option 2 is correct.