Question

What is the probability that the family has at least one boy?

(a) 0.415

(b) 0.270

(c) 0.73

(d) 0.315

The question was asked by my school principal while I was bunking the class.

The origin of the question is Probability & Experimental Approach topic in portion Probability of Mathematics – Class 9

Answer 1

Right option is (c) 0.73

The explanation: In this case, having at least one boy means one boy or two boys.

Hence, number of families having at least one boy = 415 + 315 = 730

Therefore, the probability that the family has at least one boy = \(\frac{number \,of \,families \,having \,at \,least \,one \,boy }{Total \,number \,of \,families} = \frac{730}{1000}\)

= 0.73.