Question

Explain to a grade 4 class why pencils on the table are 3/10 of the pencils, not 3/7

Answer 1

When we have 3 pencils on the table and rest of the 7 pencils are on the floor.

Then the total number of pencils $=$ pencils on table $+$ pencils on the floor

total number of pencils $=3+7=10$

Now Factor of pencils on the table = pencils on the table divided by total pencils

According to this:

Factor of pencils on the table $= \dfrac{3}{10}$( of the total pencils)

OR

In language we can say that only 3 pencils out of total 10 pencils are on the table ,so

there is $\dfrac{3}{10}$ parts of the total pencils present on the table.

In above explanation there is no mention of $\dfrac{3}{7}$ so we can say that the answer can not be $\dfrac{3}{7}$ .as denominator always contains the total no of pencils present(that is 10 and not 7).