Data question to find missing variables

• April 6th 2009, 08:14 PM
200001
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
• April 6th 2009, 10:07 PM
mr fantastic
Quote:

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

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

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

Solve equations (1) and (2) simultaneously.
• April 7th 2009, 08:56 AM
200001
Thats great. Thanks