Let A={x|x be a prime no. and x<30}.The no. of different rational nos. whose numerator and denominator belong to A is?

Asked by ADITI BHATNAGAR | 3rd Jan, 2013, 10:39: PM

Expert Answer:

as there are 10 prime no. which are less than 30.so here we have 10 options from which we need 2 numers 1 for numerator and 1 for denominator,so
no. of different rational numbers whose denominator and numerator belongs to A=10 C2
                                                                                                                  =45

Answered by  | 4th Jan, 2013, 10:46: PM

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