Answers>Maths>IB>Article

Three girls and four boys are seated randomly on a straight bench. Find the probability that the girls sit together and the boys sit together.

There is a total of 7! possible ways in which the seven children can be seated on the bench. The number of favourable arrangements when four boys are seated on one side and three girls on the other side is 4! * 3! as the boys can be sitting in any order, and so can the girls. We need to multiply this number by 2, because the boys and girls could be seated on either side of the bench, giving us twice as many possibilites. The probability is calculated as the ratio between the number of favourable arrangements and the total number of arrangements, giving us P = (4! * 3! * 2)/(7!) = (3! * 2)/(567) = (322)/(235*7) = 2/35.

Answered by Maths tutor

1890 Views

See similar Maths IB tutors

Related Maths IB answers

All answers ▸

Let Sn be the sum of the first n terms of the arithmetic series 2+4+6+... . Find (i) S4 ; (ii) S100 .


f(x)=(2x+1)^0.5 for x >-0.5. Find f(12) and f'(12)


Which are the difference between polar and coordinate complex numbers?


The sum of the first n terms of an arithmetic sequence is Sn=3n^2 - 2n. How can you find the formula for the nth term un in terms of n?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences