SOLUTION
This is a binomial probability. For i, we will apply the Binomial probability formula
i. Exactly 2 are defective
Using the formula, we have

Note that I made the probability of being defective as the probability of success = p
and probability of none defective as probability of failure = q
Exactly 2 are defective becomes the binomial probability

Hence the answer is 0.1157
(ii) None is defective becomes

hence the answer is 0.4823
(iii) All are defective

(iv) At least one is defective
This is 1 - probability that none is defective

Hence the answer is 0.5177
Answer is 174 ft2.
Area of triangle: 24 ft2
First, find the horizontal side of the triangle (using pythagorus).
16-10=6
root10^2 - 6^2 = 8 ft
Then work out the area of the triangle.
(8 x 6)/2 = 24 ft2
Secondly, find the area of the rectangle.
10 x 15 = 150 ft2
Then add up the area of the triangle and rectangle.
150+24= 174 ft2
Add them all up and if they add up to 180 then your side lengths are good