5th grade math question

Question

Bishon need to sell at least .3 of his collection of cards to make room for new cards. Is 3/20 of his collection enough?

Answer 1

In order to compare these two, we first have to get them into the same form, because right now one is a decimal and the other is a fraction and it is hard to compare them side by side like that. It does not matter which form you pick, as long as both are the same, so let us do it both ways.

Turning the fraction into a decimal is probably the easier direction here. A fraction is really just a division problem, so 3/20 means 3 divided by 20:

3 divided by 20 = 0.15

Now both numbers are decimals, and we can line them up. Bishon needs at least 0.3, and 3/20 is 0.15. If you notice, 0.15 is smaller than 0.3, in fact it is only half as big.

We can also check it the other way, by turning 0.3 into a fraction. The decimal 0.3 is three tenths, or 3/10, and to compare that to 3/20 we need a common denominator. Multiplying the top and bottom of 3/10 by 2 gives 6/20. Now they are easy to compare:

3/20 versus 6/20

Same denominator, so we just look at the tops, and 3 is less than 6.

So, our final answer is no, 3/20 is not enough. Bishon needs at least 6/20 of his collection, which is 0.3, and 3/20 is only 0.15, which is half of what he needs.

Answer 2

First, change your fraction 3/20 into a decimal.

How do we do that?

We would need to divide. Now, I always tell my students top number always go in the house when dividing, it is not always the "bigger" number.

Once when you divide, you would get the decimal, 0.15. Now, Bishon needs to sell at LEAST 0.3 of his collection, and he only sold 0.15 of his collection, and so since 0.15 is less than 0.3, selling 3/20 is not enough.

I hope this helps!