The average age of a class is 40 years. 12 new students with an average age of 32 years join the class, decreasing the average by 4 years. What was the original number of students?

The mean is found by __________ all the numbers and then __________ by the number of items.

The average temperature of a city over 5 days was 28°C. If the temperature on the first 4 days was 27°C, 29°C, 26°C, and 30°C, what was the temperature on the 5th day?

The average age of a husband, wife, and their child 3 years ago was 27 years. What is the present age of the husband?

The average score of 20 students is 75. If 5 students scored an average of 80, what is the average score of the remaining 15 students?

Find the average of the numbers: 50, 55, 60, 65, 70, and 75.

The average weight of 8 students is 60 kg. If the weight of one student is excluded, the average weight decreases by 0.5 kg. What is the weight of the excluded student?

The average of three consecutive even numbers is 14. What is the smallest of these numbers?

Find the average of the numbers: 10, 20, 30, 40, 50.

What is the average of all prime numbers between 30 and 50?