Question

The mean (average) height of 4 girls is 152 cm.

Melissa joins the group and the mean height of the
group of the 5 girls is now 151.6 cm.
What is Melissa's height?

Answer 1

Melisa's height = 150 cm

Explanation:

Initially, we are told there are 4 girls and their average height is 152 cm.

Now, the formula for this average is;

Average height = total sum of heights/number of girls

Thus;

152 = total sum of heights/4

We cross multiply to get;

Total sum of heights = 152 × 4

Total sum of 4 girls height = 608 cm

Now we are told that melissa joins them and the average height of the 5 of them is now 151.6.

Let melissa's height be x.

Thus;

Total height of 5 girls is now; (608 + x)

So, from the formula for average initially;

151.6 = (608 + x)/5

Cross multiply to get;

151.6 × 5 = (608 + x)

758 = 608 + x

Subtract 608 from both sides to get;

758 - 608 = x

x = 150 cm