Answer: $85,000
Step-by-step explanation:
Given : In a given population of two-earner male-female couples, male earnings have a mean of $40,000 per year and a standard deviation of $12,000.

Female earnings have a mean of $45,000 per year and a standard deviation of $18,000.

If C denote the combined earnings for a randomly selected couple.
Then, the mean of C will be :-

Hence, the mean of C = $85,000
Answer:
a) P = 362880 ways
b) P = 2880 ways
Step-by-step explanation:
a) We have four boys and five girls, they are going to sit together in a row of 9 theater seats, without restrictions
We have a permutation of 9 elements
P = 9!
P = 9*8*7*6*5*4*3*2*1
P = 362880 ways
b) Boys must seat together, we have two groups of people
4 boys they can seat in 4! different ways
P₁ = 4!
P₁ = 4*3*2*1
P₁ = 24
And girls can seat in 5! dfferent ways
P₂ = 5!
P₂ = 5*4*3*2*1
P₂ = 120
To get total ways in the above mentioned condition, we have to multiply P₁*P₂
P = 24*120
P = 2880 ways
Use the equation of motion under gravity:-
s = 16t^2 where s is the distance and t = time
2063 = 16t^2
t^2 = 2063 / 16 = 128.94 s
t = sqrt 128.94 = 11. 4 seconds to the nearest tenth of a second