12. In an examination 80% students passed. If 15 less had appeared and 10 less passed, the ratio of
passes to failures would have been 5 : 1. How many students passed and how many appeared in
the examination?
Answers
Step-by-step explanation:
Suppose x candidates passed and y failed; therefore,
yx=14
x=4y (1)
In the second case; no. of students appeared =x+y−30
and no. of those who passed =x−20
No of failed
N=x+y−30−(x−20)
N=y−10
from the question
y−10x−20=15
x−20=5y−50
x−5y=−30
from ( 1)
4y−5y=−30
y=30
x=120
So, x+y=150
Total number of students who appeared for the examination =150
Answer:
Student Passed in English =80%
Students failed in English=100%−80%=20%
Students passed in Maths =70%
Students failed in Maths =100%−70%=30%
Students failed in both =10%
Total failed students = Failed in English + failed in Math − Common
Total fail students =20%+30%−10%=40%
If 40% failed then 60% will be passed.
Let total students be x.
Hence, 60% of x=144
⇒
100
60
×x=144
⇒x=
60
144×100
⇒x=240
Therefore, total students is 240.