Answer:
Reject H0 if Z ≤ critical value
- 2.8747978 ≤ 1.645
Step-by-step explanation:
Setting the null and alternative hypothesis :
H0 : μ = 3.5
H1 : μ < 3.5
Sample size (n) = 40
Mean (m) = 3 minutes
Standard deviation (s) = 1.1 minutes
Test statistic : Z = (m - μ) / (s/√n)
Z = (3 - 3.5) / (1.1/√40)
Z = - 0.5 / 0.1739252
Z = - 2.8747978
Zcritical at α 0.05 = 1.645
This is a left tailed test :
Hence rejection region:
Reject H0 if Z ≤ critical value
- 2.8747978 ≤ 1.645
mixed number: 4 7/8 simplest form: (THERE IS NONE)
This is the application of trigonometry. The distance of the ladder from from the wall will be given by:
cos θ=(adjacent)/(hypotenuse)
θ=72°
adjacent=base (distance the ladder to base of the wall)= xft
hypotenuse=length of the ladder.
Therefore plugging our values in the formula we get:
cos 72=x/15
x=15 cos 72
x=4.635 ft
Hence we conclude that the foot of the ladder is 4.635 ft away from the base of the wall.
I think it A or C
i hope it help