### Chap 3: Estimation in Shopping...

The class is going to hold a snack party to celebrate the end of 1st Term!

Members of the class have drawn up the list of snacks for the Welfare committee to get from the supermarket (NTUC FairPrice):

1. Japanese Snacks
2. Snacks and Crackers
3. Dessert & Puddings
4. Household Items - Tissue/Wet Tissue
The Welfare committee made a quick estimation that the amount needed would be \$23.
Without using a calculator,
• How does the committee arrive at the figure?
• Do you think it's enough?
• Write down how (you think) the committee arrive at the figures
• Is that the most appropriate way to estimate for budget? Share your view.

1. By rounding off to one significant figure.For example...\$5.30-\$5
This is not appropriate for estimation for a budget as there will be times where the amount is rounded down. They should round everything up to make sure that there is enough money.

2. They round all the numbers to 1SF.
This is not the most appropriate way to estimate for budget as there might some decimals which might add to another dollar or two. They should round all the numbers up hence will not exceed the budget.

3. I believe the committee arrived at the figure by rounding off to 1 significant figure, as in rounding down. No, as when you round down, the amount of money needed when you need to pay for the items will definitely not be enough since you reduce some of the original value.

chengngee

4. The committee arrived at the figures by rounding off to 1 significant figure.

This is not the most appropriate way to estimate the budget because the amount may not be enough. The class committee should round up the cost so that the amount will be enough.

5. The committee estimated the figures by rounding each of them to the 1st significant figure. I do not think that it will be enough as \$23 is not the exact amount and it can be higher or lower than the real total budget of all the items. But it is probably the most accurate way and it is a fast method.

6. The committee got to this number by rounding of all the numbers to 1 significant numbers.No i do not think it is enough as if u do it to 2 significant numbers it is more accurate and the result is more than \$23

7. The committee used approximation to calculate the figure. I do not think it is enough as the committee rounded down the figures. So,I think it is the most appropriate way to estimate.

8. I think they arrived at this figure by estimating the total price to one significant figure.
I think it is not a very appropriate way to estimate the figure as it would be a bit out of the original price for the total price of the items.

9. a) multiply the quantity with the price which has been rounded to 1 significant figure.

b) round up the price to a whole number so that there are higher chances of having enough money.

10. The committee rounded of the cost of each item to 1 significant figure, and added the total value. I do not think \$23 is enough because after rounding off to 1 significant figure, the total cost of the items in \$27.

I do not think that is the best way to estimate the budget. There are many other ways like calculating the total value first, then rounding it off the total value to 1 significant figure.

11. They arrived at the figure by rounding off the numbers to the nearest whole number.

No, it is not the most appropriate way to estimate a budget as there is extra change needed to buy each item, and the amount will not be exact. Usually, there will not be enough money.

12. The commitee arrive at the figure by rounding off the amount of money of each items to the 1st significant figure. I do not think it is sufficient as \$23 is a rough estimation and the amount can be more than that.

13. The committee rounded off the numbers to the nearest whole number.

It is not the most appropriate way to estimate as the amount may sometimes be rounded down. Thus, the budget will be too little for the snacks.

14. The committee arrived at the figure by rounding off all the price to 1 significant figure. They then multiply the price by the quantity of each item, getting \$23.

I think it is not enough as all the sum is being rounded down and not up. Therefore, there will be a shortage of money in the end. They should have overestimated the sum instead of underestimating the sum.

15. All the figures should be rounded up instead of down so that we would guarantee have enough money to buy the items needed
Another way is to round the numbers to two significant figures

16. I think that the committee rounded off each pricing to 1 significant figure, therefore coming up with the figure, \$23.

I do not think this is the most appropriate way to estimate for budget because it is too general. The committee will have to pay more than \$23 for all the items. They should at least round off to 2 significant figures.

17. a) They rounded of to 1 significant figure.

b) They should have not rounded at all and find the exact figure as it is not accurate enough and may be rounded down.

18. The committee rounded off the sum to one significant which is the easiest. No, i don't think its enough because there are some extra cents for each product which isn't counted.
The committee rounded off the sum to one significant.
No it is not the most appropriate method to estimate the budget. We should estimate it to at least two significant figure.

19. The committee rounded off the numbers to the nearest whole number.

Most of the numbers have been rounded down, therefore \$23 may not be enough .

20. They rounded off the prices of the items to 1 significant figure.

It will not be enough as when the prices were rounded off to 1 significant figure, more amount of money would be subtracted from the actual sum than added to it.

21. The committee rounded off each and every of the prices of the snack to 1 significant figure, as such the resulting amount would not be accurate. Some of the products are round down which may result in insufficient funds.

As such the committee should calculate the total amount and round up the prices to whole numbers, this way it can result in having enough funds to buy the snacks.

22. a)They have rounded off to one significant figure.

b)They should round of to 2 significant figures as it is more accurate.