Word problem help

Question

Hi, I have been working on some word problems and just do not know how to go about dealing with these two word problems, any help is much appreciated. 

 

- Seven piles of bricks are placed side by side so that their tops form steps 1 brick high. If the lowest pile contains 9 bricks, how many bricks are being used altogether?

 

- A contractor agrees to complete a house in 250 days, and to do this he engages 60 men. After 200 days no work is done for 10 days. How many extra men must he engage to finish the house in time?

 

 

Thank you

Answer 1

Hi Harsimren, here's how to do them.

(a) Lowest step is 9 bricks high. So, next step is 10 bricks, and then 11, etc.

The pattern here is the # of bricks = step # + 8. Therefore, the 7th step is 7 + 8 = 15 bricks high.

Now, for the total # f bricks, we just need the sum of 9 + 10 + 11 + . . . + 15.

I leave that as exercise for you.

(b) The contractor needs extra workers to complete 50 days' work in only 40 days (since 10 days were lost.)

This is a standard proportion problem: To complete in 50 days requires 60 workers

To complete in 40 days requires x workers

x = (50 / 40) x 60

= 75 workers

Therefor, the contractor must hire an extra 15 workers.