Answer:
His age is 7 years.
Step-by-step explanation:
Let Rehman's present age be x years.
1 / (x - 3) + 1 /(x + 5) = 1/3
Multiply through by the LCD 3(x - 3)(x + 5):
3(x + 5) + 3(x - 3) = (x + 5)(x - 3)
3x + 15 + 3x - 9 = x^2 + 2x - 15
x^2 + 2x - 6x - 30 + 9 = 0
x^2 - 4x - 21 = 0
(x - 7)(x + 3) = 0
x = 7 (answer).
I got 3/8, hope this helps.
By "density" I assume you mean "probability density function". For this to be the case for

, we require

Since

you have

which means
Answer:



Step-by-step explanation:
Given
Let
A = Event of being a universal donor.
So:


Solving (a): Mean and Standard deviation.
The mean is:



The standard deviation is:




Solving (b): P(x = 3)
The event is a binomial event an dthe probability is calculated as:

So, we have:



