The lifetime of disc brake pads varies according to a normal distribution with mean μ = 50,000 miles and standard deviation σ = 3000 miles. (a) What is the probability the lifetime of a random sampled brake pad is 47,000 miles or less? (b) What is the distribution of the mean lifetime X of 9 randomly sampled brake pads? (c) What is the probability the mean lifetime of 9 randomly sampled brake pads is less than 47,000 miles?

your answer would be 12

place r′ so that qr′ is parallel to the tangent.

now we get that ∠r′py=∠pr′q, where y is on the tangent, on the opposite side of p from x.

also, because of the symmetry, ∠r′py=∠qpx.

finally, note that no matter where we place r, as long as it's on the correct arc, we have ∠prq=∠pr′q.

stringing all these equalities together, we end up with ∠prq=∠qpx.

this picture will show how its going to look like.

hope this by jack monhen