The distance traveled by the balloon in every minute makes an arithmetic sequence with a first term equal to 40 ft and common difference equal to 20. The nth term of an arithmetic sequence is calculated by,
an = a1 + (n - 1) x d
Substituting,
an = 40 + (15 - 1) x 20 = 320
Thus, the answer is letter B. 320 feet.
The probability is zero because there is only red green and blue
-11 = -2 + x/4
x/4 = -11 + 2 = -9
x = 4(-9) = -36
