Hi,

Can someone out there comment on my solution to the following question and offer solution using model?

40 boys had to paint some Easter eggs. One of them fell sick and the rest of the boys had to paint 3 more each. How many Easter eggs did they have to paint altogether?

40 - 1 = 39
39 x 3 = 117
117 x 39 = 4563

Darryl See wrote:
Hi,

Can someone out there comment on my solution to the following question and offer solution using model?

40 boys had to paint some Easter eggs. One of them fell sick and the rest of the boys had to paint 3 more each. How many Easter eggs did they have to paint altogether?

40 - 1 = 39
39 x 3 = 117
117 x 39 = 4563

Model is not practical for such big numbers. i.e. you would be drawing too many blocks.In place of model blocks use units.

Method 1
40U-39U = 1U -> 39 x 3 =117
40U = 117 x40 =4680

Explanation for Method 1:
Lets say initially 40 boys painted 40 units
39 boys would have painted 39 units if each painted the same number

The difference in 40 units and 39 units is 1 unit. i.e. 40U-39U = 1U

This difference was made up by the 39 boys each painting 3 more eggs i.e. 39 x 3 =117

i.e. 1U = 117

The number of eggs painted by 40 boys was 40U i.e. 40 x117 =4680

Method 2 coming up next

Method 2

We can actually have a more direct approach without unit method, models; but using pure logic giving a straight 2 step solution.

Working Method 2

39 x3 = 117
40 x117 = 4680 (ans)

Explanation Method 2

39 boys painting 3 eggs would mean they would have painted 39x3=117 eggs to cover 1 missing boy from the original team of 40.

i.e. the missing boy caused a shortage of 117 eggs

i.e. each of the 40 boys had painted 117 eggs i.e. 40 x117 = 4680

this time i put in the correct place

Wow!

You guys are great. Thank you very much.

Darryl See wrote:
Hi,

Can someone out there comment on my solution to the following question and offer solution using model?

40 boys had to paint some Easter eggs. One of them fell sick and the rest of the boys had to paint 3 more each. How many Easter eggs did they have to paint altogether?

40 - 1 = 39
39 x 3 = 117
117 x 39 = 4563


[...][...][...]..................[39x3] ................ 40 boys

1 boy -- 39 x 3 = 117

40 boys -- 117 x 40 = 4680 Easter eggs