H(t) = f(t) - g(t)
= 500(1.2)^t - 380(1.15)^t
Taking out the greatest common factor, which is 20:
= 20[(25)(1.2)^t - (19)(1.15)^t]
This is the third choice.
Note that you cannot subtract the bases of the exponents, for example (1.2^t - 1.15^t) cannot be simplified into something like 0.05^t.
The probability p of an orangecandy is 0.2. The sample size = 100.
The mean is given by:

The standard deviation is given by:

The answers are: Mean = 20. Standard deviation = 4.
Her friend's house is 1/12 miles away from her house.
Since 1/4 miles is 1/3 of the way, 1/4 x 1/3 = 1/12.