# Thread: Data question to find missing variables

1. ## Data question to find missing variables

The table shows the weights of 100 children in class 1.
An estimate of the mean weight of the children is calculated as 44 kg.
Calculate the values of a and b.

w (kg) Frequency
20 < w <30 12
30 < w < 40 21
40 < w < 50 38
50 < w < 60 a
60 < w < 70 b

Answer a = ........................... , b = ...........................

ps last < should be greater OR equal to

How do I go about starting the problem?
Regards

2. Originally Posted by 200001
The table shows the weights of 100 children in class 1.

An estimate of the mean weight of the children is calculated as 44 kg.
Calculate the values of a and b.

w (kg) Frequency
20 < w <30 12
30 < w < 40 21
40 < w < 50 38
50 < w < 60 a
60 < w < 70 b

Answer a = ........................... , b = ...........................

ps last < should be greater OR equal to

How do I go about starting the problem?

Regards
$\displaystyle 12 + 21 + 38 + a + b = 100$ .... (1)

$\displaystyle \frac{12 \times 25 + 21 \times 35 + 38 \times 45 + a \times 55 + b \times 65}{100} = 44$ .... (2)

Solve equations (1) and (2) simultaneously.

3. Thats great. Thanks