Answer:
Probability that one of them is mathematics and other two are either physics or history books = 0.51
Step-by-step explanation:
Given - A student needs to select 3 books from 3 different mathematics, 3 different physics and 1 history books.
To find - What is the probability one of them is mathematics and other two are either physics or history books ?
Solution -
Given that,
A student needs to select 3 books from 3 different mathematics, 3 different physics and 1 history books.
So,
Total number of books = 3 + 3 + 1 = 7
The student has to select 3 books
So, Total number of ways =
= 35
So,
Probability that one of them is mathematics and other two are either physics or history books is -
= 
= 
= 
= 0.51
⇒Probability that one of them is mathematics and other two are either physics or history books = 0.51

square root of negative is an imaginary solution or number. meaning it exist somewhere. square root of 64 is 8 and the square root of 25 is 5. "i" represent imaginary number