Averages Questions

There are five numbers. The second number is 25% more than the first or third number, the fourth number is 5/4 of the third number and the fifth number is 3/2 of the third number. What is the average of the five numbers if the first number is 40?

The average weight of students in a class was 60.5 kg. When 8 students, whose average weight was 65 kg, joined the class, then the average weight of all the students increased by 0.9 kg. The total number of students now in the class is:

The average age of 6 brothers is 15 years. The age of the youngest brother is 5 years. What was the average age (in years) of the group of brothers at the time of birth of the youngest brother?

The average height of 20 students of Class 9 is 147cm and the average height of $15 students of Class 10 is 154cm. What is the average height (in cm) of the students of the two Classes?

The average of the numbers 52,87,k,103,48,(k+4),51 is 63. What is the value of k?

There are five numbers whose average is 72. If the first number is one-fifth of the sum of the other four numbers, then the first number is:

The average weight of $35$ apples is $50$ grams. If some apples of weight $40$ grams each were removed, then the average weight becomes $57.5$ grams. How many apples of weight $40$ grams were removed?