Answer:

Step-by-step explanation:
step 1
Find the 
we know that
Applying the trigonometric identity

we have

substitute





Remember that
π≤θ≤3π/2
so
Angle θ belong to the III Quadrant
That means ----> The sin(θ) is negative

step 2
Find the sec(β)
Applying the trigonometric identity

we have

substitute




we know
0≤β≤π/2 ----> II Quadrant
so
sec(β), sin(β) and cos(β) are positive

Remember that

therefore

step 3
Find the sin(β)
we know that

we have


substitute

therefore

step 4
Find sin(θ+β)
we know that

so
In this problem

we have




substitute the given values in the formula



Given:
μ = $3120, population mean
σ = $677, population standard deviation.
The population is normally distributed.
n = 20, sample size.
At the 95% confidence level, the confidence interval is

1.96(σ/√n) = 1.96(677/√20) = 296.71
Th confidence interval for the mean is
($2823.29, $3416.71)
Answer: ($2823.29, $3416.71)
The given proportion is expressed as
y/5 = 7/8
If we crossmultiply, it becomes
y * 8 = 7 * 5
8y = 35
y = 35/8
y = 4.375
Rounding to the nearest tenth,
y = 4.4
(180 miles=7.5 hours, 20 miles=2.5/3=0.8333) 7.5+0.8333=8.3333 or 8h and 20 minutes.