The average of 10 observations is 21. A new observation is included and the average of these 11 numbers is 1 less than the prevoius average. The 11^th observation is____

The average weight of 12 parcels is 1.8 kg. Addition of another new parcel reduces the average weight by 50 g. What is the weight of the new parcel?

If the average marks of three batches of 30, 50 and 70 students is 55, 70 and 70 respectively, then the average marks of all the students is:

The heights of six people are given as 6 feet 6 inches, 6 feet, 5 feet 8 inches, 6 feet 2 inches, 6 feet 4 inches, and 5 feet 10 inches, respectively. Find the average height of these six people.

There are two groups A and B of a class, consisting of 42 and 28 students respectively. If the average weight of group A is 25 kg and that of group B is 40 kg, find the average weight of the whole class. 

Average weight of 25 students of a class is 50 kg. If the weight of the class teacher is included, the average is increased by 1 kg. The weight of the teacher is 

Answer the following questions

In an exam of 100 marks, the average marks of a class of 40 students are 76. If the top 3 scorers of the class leave, the average score falls “down by 1. If the other two toppers except “the highest topper scored not more than 85. “then what is the minimum score the topper can score?

Average age of mother, father and son was 42 at the time of son's marriage. After one year, an infant was born and after 6 rears of marriage the average age of family becomes 36. Find the age of bride at the time of marriage.