Answer :
Answer:
9n/60
Step-by-step explanation:
add 1/12 + 1/15 which = 5/60 + 4/60.
= 9/60
YAY!!!!!!!
The fraction of the exams that Mr Tough and Mrs Nice grade in 1 hour if they work together is 3/20
What are fractions?
In Maths, a fraction is used to represent the portion/part of the whole thing. A fraction has two parts, namely numerator and denominator. There are proper fractions, improper fractions and mixed fractions.
Example: 2/5, 1/4 etc.
How to solve Work and Time problems:
We will this equation,
rate × time = work done
For this problem:
Mr Tough's rate:
Mr Tough's rate × 12 hours = final exam
Mr Tough's rate = 1/12
Mrs.Nice's' rate:
Mrs .Nice's' rate × 15 hours = final exam
Mrs .Nice's' rate = 1/15
To make this into a solvable equation, find the total time (T) needed for Mr Tough and Mrs.Nice to grade the final exam. This time is the sum of the rates of Mr Tough and Mrs.Nicea, or:
Total time:
T(1/12 hours + 1/15 hours) = final exam
T = final exam / (1/12 + 1/15)
Simplifying we get,
T = final exam / (0.15)
Now, to finish in 1 hour we will find what fraction of the final exam they can grade, so taking T = 1 hour,
1 hour = final exam / (0.15)
By further simplifying,
final exam = 1 × 0.15
= 0.15
= 15/ 100
= 3/20
Therefore, 3/20 fraction of the final exam they can grade if they work together for 1 hour.
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