Problem of the Week 7

My apologies for not sustaining the Problem of the Week section of this site. Anyway, I’ll do my best to make Problem of the Week a really weekly post. This week, we are going to tackle two problems since they are quite easy. These problem are classified under the third Grade and were taken from Grade 3 Sample Problem Set 1, so these are actually very easy.

Problem 1

My uncle’s age is 7 more than twice my eldest brother’s age. My eldest brother is 19 years old. How old is my uncle?


The eldest brother’s age is 19. The uncle’s age is 7 more than twice the brother’s age. Now, twice 19 is equal to 38. Since the uncle is 7 more than twice, we add 7 to 38. So, the uncle is 38 + 7 = 45 years old.

Correct Answer: 45 years old

Problem 2

Ricky has 84 marbles, 1/3 of the marbles are green, 2/4 are red and the rest are white.How many marbles of each color are there?

via Wikipedia


First, we get the number of green marbles.

1/3 of 84 is the same as 84/3 which is equal to 28.

Next, we get the number of red marbles which is 2/4 of 84. This is the same as half of 84. Remember that 2/4 is the same as 1/2 and we know that half of 84 equals 42.

So, the number of green marbles and the number of red marbles is 28 + 42 = 70 marbles.

Since there are 84 marbles in all, the remaining number of marbles which are the white marbles is 84 – 70 = 14.

Correct Answer: 28 green marbles, 42 red marbles, and 14 white marbles

Thank you for reading. Til the next problem of the week!

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