self Maths Puzzle

there are 10 pairs of socks in a cupboard from which four individual socks are picked at random.the probability that there is at least one pair is?

Read Solution (Total 2)

at least one means 2 also possible.so ans is 10c1+10c2/10c2
11 years agoHelpfull: Yes(0) No(4)

(10C1*10C3+10C1*10C3+10C2*10C2)/20C4
11 years agoHelpfull: Yes(0) No(2)

self Other Question

Consider a two digit number x and and another number y with x's digits reversed which of the following cannot be x+y, indicate all that apply?
option
a) 121
b) 220
c) 111
d) 110
e) 187 the ratio of the monthly incomes of A and B is 3:4. The ratio of the monthly expenditures of A and B is 4:5. Which of the following representation possible value of the ratio of their savings?