Statistics Test...

An automobile driver travels from plane to a hill station 120 km distant at an average speed of 30 km per hour. He then makes the return trip at an average speed of 25 km per hour. He covers another 120 km distance on plane at an average speed of 50 km per hour. His average speed over the entire distance of 360 km will be

The average weight of students in a class of 35 students is 40 kg. If the weight of the teacher be included, the average rises by 1/2 kg; the weight of the teacher is

The A.M. of n observations is M. If the sum of n – 4 observations is a then the mean of remaining 4 observations is

If the mean of the distribution is 2.6, then the value of y is
Variate x 1 2 3 4 5
Frequency f of x 4 5 y 1 2

In a class of 100 students there are 70 boys whose average marks in a subject are 75. If the average marks of the complete class are 72, then what are the average marks of the girls

The harmonic mean of 4, 8, 16 is

Mean of 100 items is 49. It was discovered that three items which should have been 60, 70, 80 were wrongly read as 40, 20, 50 respectively. The correct mean is

A school has four sections of chemistry in class XII having 40, 35, 45 and 42 students. The mean marks obtained in chemistry test are 50, 60, 55 and 45 respectively for the four sections, the over all average of marks per students is