Question

please answer this question.it's urgent.

Answer 1

let


p = the number of passes

f = the number of failures

p + f = the number of the people that appeared at the examination


the ratio of passes to failures was 4:1


P : f = 4 : 1

p = 4f


if 30 less had appeared and 20 less passed,the ratio of passes to failures would have been 5:1


30 less had appeared: p + f - 30


20 less passed: p - 20


number of failures: p + f - 30 - (p - 20) = p + f - 30 - p + 20 = f - 10


the ratio of passes to failures would have been 5:1


(p - 20) : (f - 10) = 5 : 1


p - 20 = 5(f - 10)


by solving the system of equations


p = 4f

p - 20 = 5(f - 10)


we find


p = 120 passes


f = 30 failures

p + f = 150


150 students appeared for the examination.
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