NIMCET 2008 Question Paper with solutions

© examsiri.com

Question : 34 of 120

Marks: +1, -0

Suppose

P_{1}, P_{2}, . . ., P_{30}

are thirty sets each having 5 elements and

a_{1}, a_{2}, . . ., a_{n}

are

n

sets with 3 elements each. Let

⋃↙{{i=1}}↖{{30}} P_{i}=⋃↙{{j=1}} ↖{{n}} Q_{j}=S

and each element of

S

betongs to exactly 10 of the

P_{i} s

and exactly 9 of the

Q_{j} s

. Then

n

is equal to

15
3
45
None of these

Solution:

∑ P_{j}=(U P_{j}) × 10

and

\;\; ∑ Q_{j}=(U Q_{j}) × 9

⇒ 10 S =30 × 5

⇒ S =15

Also,

3 n=9 S

⇒ \;\; n=3 S=45

© examsiri.com

Go to Question:

Prev Question

Next Question