Campus Recruitment Non-Tech Quiz-4

The average of five positive numbers is 56. If the first number is three-fourth of the sum of the last four numbers, then the average of the last four numbers is:

Two solutions of alcohol A and B were mixed to obtain 20 litres of new solution C. Before they were mixed, the first solution A contained 1.6 litres of alcohol while the second solution B contained 1.2 litres of alcohol. Before mixing if the percentage of alcohol in the first solution A was twice that in the second B, what was the volume of the first solution A before mixing?

Ankit can complete a work in 10 days, Bhanu in 12 days and Chinmoy in 15 days. All of them began the work together, but Ankit had to leave after 2 days and Bhanu 3 days before the completion of the work. The total number of days in which the work got finished is

A group of boys and girls know either French or Spanish. The number of boys and girls are in the ratio 1 : 4. 30% of the girls know Spanish and the rest of them know French. On the other hand, 50% of the boys know Spanish and the rest of them know French. A student is chosen at random from the group of students who knows Spanish. What is the probability that the chosen student is a girl?