ILLUSDUCA wrote:Hello Jeff!JeffLim wrote:Hi there,

Need help on this.

The average mass of a group of boys is 45 kg.Ifone more boy who weighs 75 kg joins the group, the new average mass of the group will become 48 kg. Find the total number of boys in the group.

Thank you in advance.

Jeff

Here's one way to do this:

75kg - 45kg = 30kg difference

48kg - 45kg = 3kg difference

30/3 = 10 students (9 of them weighing average of 45kg and 1 of them weighing 75kg)

Hope this helps!

Hi,

The answer sh be

**9 boys**,

as the boy who weighs 75 kg did

**NOT**actually join the group.

Cheers

**speedmaths**

.