Mathematics (Pri 5) : Average (MCQ - 1)

Explanation
The average number of stickers each of them has can be found by adding up the number of stickers each person has and dividing it by the total number of people. In this case, Simon has 72 stickers, Theodore has 88 stickers, and Alvin has 98 stickers. Adding these numbers together gives us 72 + 88 + 98 = 258. Since there are three people in total, we divide 258 by 3 to get an average of 86 stickers per person.

Explanation
The average amount of money Mei Ling and Fu Hua have can be found by dividing the total amount of money they have ($48) by the number of people (2). So, the average amount of money is $24.

Explanation
The average mass of the 6 boxes is 5.65 kg. In order to find the total mass of the 6 boxes, we can multiply the average mass by the total number of boxes. So, 5.65 kg multiplied by 6 gives us 33.9 kg. Therefore, the correct answer is 33.9 kg.

Explanation
To find out how many marks David must score in the 4th test, we need to calculate the average of all 4 tests. Since David wants his average mark to be 5 more than his previous average mark, we add 5 to his previous average mark of 65. Therefore, the new average mark should be 70. To calculate the total marks David needs to achieve this average, we multiply the new average (70) by the number of tests (4), which gives us a total of 280. Since David has already scored 65 marks in the first 3 tests, he needs to score 215 marks in the 4th test to achieve an average of 70.

Explanation
If the average mass of Caili and her three sisters is 42kg, and Caili weighs 48kg, the total mass of Caili and her three sisters combined is 42kg x 4 = 168kg. Since Caili weighs 48kg, the total mass of her three sisters is 168kg - 48kg = 120kg. To find the average mass of her three sisters, we divide the total mass by the number of sisters, which is 3. Therefore, the average mass of her three sisters is 120kg / 3 = 40kg.

Explanation
The average of three numbers is found by adding them together and then dividing by the total number of numbers. In this case, the average is 26. Since two of the numbers are given as 11 and 21, we can find the third number by subtracting the sum of the given numbers from the total average. Therefore, the third number is 26 - (11 + 21) = 46.

Explanation
Let the savings of each boy be x. Since each girl saves $50 more than each boy, the savings of each girl would be x + $50. The average savings of 2 girls and 2 boys is $250, so (2x + 2(x + $50))/4 = $250. Simplifying this equation, we get 4x + 2x + $100 = $1000. Combining like terms, we have 6x + $100 = $1000. Subtracting $100 from both sides, we get 6x = $900. Dividing both sides by 6, we find that x = $150. Therefore, the savings of one boy is $150.

Explanation
Bag X weighs 4.8kg and Bag Y is 0.8kg heavier than Bag X. To find the average mass of the two bags, we can add the masses of the two bags and divide by 2. Adding 4.8kg and 0.8kg gives us 5.6kg. Dividing this by 2 gives us an average mass of 2.8kg. Therefore, the correct answer is 5.2kg.

Explanation
Jia En has 168 stickers. Hui Ling has 32 more stickers than Jia En, so Hui Ling has 168 + 32 = 200 stickers. Wan Yee has 40 fewer stickers than Hui Ling, so Wan Yee has 200 - 40 = 160 stickers. To share the stickers equally, they need to divide the total number of stickers by the number of people, which is 3. So, each person should have 168 + 200 + 160 / 3 = 176 stickers. Since Hui Ling has 200 stickers and they need to have 176 stickers each, Hui Ling should give away 200 - 176 = 24 stickers.

Explanation
Jonathan spent an average of $4.20 per day for 6 days. If he spent $5.25 for the seventh day, the total amount of money he spent for the 7 days is $4.20 * 6 + $5.25 = $25.20. To find the average amount of money he spent per day, we divide the total amount by the number of days: $25.20 / 7 = $3.60. Therefore, the correct answer is $3.60.