In a locality of 40 houses, each house is subscribed to at least one

Option-D
Sol: Solution using the overlapping sets formula (if nothing else works out for you)

Designate Sun as "S", Daily Mail as "D" and Daily Mirror as "M"

Total House = 40 ---> P(S u D u M) = 40
Each House has at least 1 ---> P(Neither)=0
24 houses subscribe to Daily Mirror ----> P(M)=24
13 houses subscribe to both The Sun and Daily Mirror ----> P(M n S) = 13
26 houses subscribe to Daily Mail out of which 16 also subscribe to The Sun -----> P(D) = 26 and P(S n D) = 16
7 houses subscribe to all three newspapers - P (S n D n M) = 7
There is no house which subscribes to The Sun alone: If no house subscribes to The Sun alone, P(S) = P(S n D) + P (M n S) - P (S n D n M) = 13+16-7 = 22
(The intersection of the three is subtracted because it is counted twice)

Now,
P(S u D u M) = P(S) + P(D) + P(M) - P(S n D) - P(D n M) - P(M n S) + P (S n D n M)

From above, P(D n M) can be calculated as 10.

Only 2 are given as : P(S n D) + P(D n M) + P(M n S) - 3*P (S n D n M) = 10 + 13 + 16 - 3*7 = 18

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