9/15
6/10
12/20
15/25
18/30
Hope this helps!! :)
a)
has CDF


where the last equality follows from independence of
. In terms of the distribution and density functions of
, this is

Then the density is obtained by differentiating with respect to
,

b)
can be computed in the same way; it has CDF


Differentiating gives the associated PDF,

Assuming
and
, we have


and


I wouldn't worry about evaluating this integral any further unless you know about the Bessel functions.
Answer:
225 thousand.
Step-by-step explanation:
You are dividing the number in half every time.
37 students get at most 67 scores.
The numbers 60-67 represent the lower quartile (lowest 25%). 25% of 60 is 15 not 30. Therefore it is incorrect.
The 3's cancel giving you the answer of 1/2