How to calculate pass % in both subjects given student failing %

Question

Problem:

In an Examination,35% fail in maths and 25% fail in English.If 10% fail in both the subjects.Then how much % pass in both?

Solution:

I applied the formula:

P(M)=Percentage of people fail in maths=35%.

P(E)=Percentage of people fail in english=25%.

P(M U E)=Percentage of people fail in in maths or english. P(M U E)=P(M)+P(E)-P(M intersection E)

35%+25%-10%=50% fail in either of the subjects.

But I am unable to calculate how to calc pass % in both subjects?

Can anyone guide me how to solve this problem?

score 1 · Answer 1 · answered Mar 26 '17 at 12:55

1

De Morgan's law is $$\mathrm{not}(A\ \mathrm{or}\ B)=(\mathrm{not}\ A)\ \mathrm{and}\ (\mathrm{not}\ B)$$ So if they don't (fail math or fail English) then...

answered Mar 26 '17 at 12:55

Matt Samuel

58,164

Not Understood Can you explain more clearly – Jalaj Chawla Mar 26 '17 at 12:58
@Jalaj I'm not sure if I can. Is there any specific thing that needs clarification? – Matt Samuel Mar 26 '17 at 12:59
@MattSamuel "pass both" means "not fail a and not fail be" – Stella Biderman Mar 26 '17 at 13:20
@Stella Yes, which is the negation of "fail a or fail b,." – Matt Samuel Mar 26 '17 at 13:21
@MattSamuel Yes. And you can't see how to answer the question from here? – Stella Biderman Mar 26 '17 at 13:27
@Stella Not sure you realize but I'm actually the answerer! I have a PhD in math, this is only slightly challenging for me :) – Matt Samuel Mar 26 '17 at 14:07
@MattSamuel Oh whoops, confused you and the OP. – Stella Biderman Mar 26 '17 at 14:10
@JalajChawla see above comments. – Stella Biderman Mar 26 '17 at 14:11

How to calculate pass % in both subjects given student failing %

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