Answer:

Step-by-step explanation:

The old photocopier can make x manuals in an hour. The new photocopier can make 4x. Combined, they made 5x manuals in an hour.
In one hour they can make 1/28 of the manuals.
1/(28*5)=1/140 is the rate.
The new photocopier can make all the manuals in 4/140 or 35 hours.
The old one can make them in 140 hours.
Answer:
5.29
Step-by-step explanation:
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