Question

In a study of 205 adults, the mean heart rate was 75 beats per minute. Assume the population of heart rates is known to be approximately normal with a standard deviation of 8 beats per minute. What is the 95% confidence interval for the mean beats per minute?

Answer 1

a) 73.9-76.1
b)73.7-76.1
c)73.9-76.3
d)70.9-73.3

Answer 2

@mathstudent55
@kirbykirby

Answer 3

@Hero
@amistre64
@dan815

Answer 4

\[\hat p\pm z(SE)\]

Answer 5

in this case

p hat is the sample mean
z is related to 95% about the mean
and SE is as it always is: sigma/sqrt(n)

Answer 6

okay, so what would be the next step? I am very confused. @amistre64

Answer 7

well, everything is defined for you, might need to look up the z score that relates to the 95% stuff tho

Answer 8

would the answer be C?

Answer 9

x bar is normally used instead of phat for means ..... but its the same run down

im not sure what the answer is, i havent worked the problem.

show me how you arrive at C

Answer 10

I plugged the values given in the question to the equation you listed

Answer 11

let me verify it then

Answer 12

the wolfs gone wacky .... im thinking 1.96 for the z score,

75-1.96(8/sqrt(205))

but then 75 is not the midpoint of C so it cant be it.

Answer 13

with that formula ^ I got -41.46?

Answer 14

@amistre64

Answer 15

i got 73.9, but not C

Answer 16

so A. @amistre64

Answer 17

i get A out of it, assuming 1.96 is the proper z value ... wich im like 96% sure of lol

Answer 18

i gotta run so good luck

Answer 19

thanks