1) This probability is given by
... C(40,5)·0.12⁵·0.88³⁵ ≈ 0.18665 . . . . . where C(n, k) = n!/(k!(n-k)!)
2) This probability is given by
... 0.88⁴⁰ ≈ 0.00602
3) This is the complement of the probability that all have failed.
... 1 - 0.12⁴⁰ ≈ 1.0000
Answer:
-35
Step-by-step explanation:

I got this by multiplying the numerator by 7. This allows the denominator to be the same as the numerator, thus equalling 1.
1 * a = a
The younger brother will be 48 when Adam is 50