If the value of 21 a + 21 b = 1134, what is the average of a + b?

AVERAGES :

The average amount with a group of eight members is Rs.30.  If the newly joined member has Rs.65 with him, what was the average amount with the group before his joining the group?

AVERAGES :

A iron manufacturing company produced a total of 3000 tons of iron in January of a particular year. Starting from February its production increased by 200 tons every month over the previous months until the end of that year. Find its average monthly production (in tons) for that year.

AVERAGES :

The average weight of a group of boys is 40 kg. After a boy of weight 48 kg joins the group, the average weight of the group goes up by 1 kg. Find the number of boys in the group originally.

AVERAGES :

The average runs scored by a batsman in 10 matches is 60. In the next 20 matches, the batsman scored an average of 30 runs. Find his average in all the 30 matches.

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The average height of 40 boys in a class was calculated as 200 cm. It was later found that the height of one of the boys in the class was wrongly written as 300 cm whereas his actual height was 200 cm. Find the actual average height of the boys in the class? (approx value)

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The average age of five persons sitting in a row facing north is 30 years. If the average age of the first two persons is 20 years and the average age of the last two persons is 35 years, then find the age of the person sitting in the middle of the row?

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The present average age of a family of five members is 30 years. If the present age of the youngest member in the family is 14 years, then what was the
average age of the family at the time of the birth of the youngest member?

AVERAGES :

The average of four positive integers is 80. The highest integer is 160 and the least integer is 20. The difference between the remaining two integers is 20. Which of the following integers is the higher of the remaining two integers?

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The average mark of the students of a class in a particular exam is 60. If 10 students whose average mark in that exam is 20 are excluded, the average mark of the remaining will be 80. Find the number of students who wrote the exam?

AVERAGES :

The average height of 100 people in a class is 200 cm. Five of them whose average height is 400 cm, leave the class and five others whose average height is 100 cm, join. The new average height of the pupils of the class (in cm) is_______