Answer:
d. 126; 70
Step-by-step explanation:
given that Ron finds 9 books at a bookstore that he would like to buy, but he can afford only 5 of them.
Out of 9 books he has to select 5 of them
Here selection of books can be done in any order. Hence order does not matter
No of ways he selects 5 books out of 9 books = 9C5
= 126
Part II
One book is a must
Hence he has options only 4 books from the remaining 8.
No of ways when one book is compulsory = selecting 3 books from 8 books
= 8C4
= 70
Option d is right.
Answer:
a) 0.96
b) 0.016
c) 0.018
d) 0.982
e) x = 2
Step-by-step explanation:
We are given with the Probability density function f(x)= 2/x^3 where x > 1.
<em>Firstly we will calculate the general probability that of P(a < X < b) </em>
P(a < X < b) =
=
=
{ Because
}
=
=
=
=
a) Now P(X < 5) = P(1 < X < 5) {because x > 1 }
Comparing with general probability we get,
P(1 < X < 5) =
=
= 0.96 .
b) P(X > 8) = P(8 < X < ∞) = 1/
- 1/∞ = 1/64 - 0 = 0.016
c) P(6 < X < 10) =
=
= 0.018 .
d) P(x < 6 or X > 10) = P(1 < X < 6) + P(10 < X < ∞)
=
+ (1/
- 1/∞) = 1 - 1/36 + 1/100 + 0 = 0.982
e) We have to find x such that P(X < x) = 0.75 ;
⇒ P(1 < X < x) = 0.75
⇒
= 0.75
⇒
= 1 - 0.75 = 0.25
⇒
=
⇒
= 4 ⇒ x =
Therefore, value of x such that P(X < x) = 0.75 is 2.
The correct answer is 2a^2