Estimating/ Rounding Errors

Question 1

Estimate the value of 42.6 x 12.1.

Answer 1

400

Question 2

Lisa has a cake-making business. She spent £984.69 on flour last year. A bag of flour costs £1.89 and she makes an average of 5 cakes from each bag of flour. Work out an estimate of how many cakes she made last year.

Answer 2

2500

Question 3

Estimate the value of 22.3 X 11.4/ 0.532

Answer 3

400

Question 4

Paloma buys 17kg of turnips at a cost of £1.93 per kg. Estimate the total cost.

Answer 4

£40

Question 5

The mass of a cake is given as 2.4kg to the nearest 0.1kg. Find the interval within which m, the actual mass of the cake, lies.

Answer 5

2.35kg /^m^ 2.45kg

Question 6

The length of rope A is 120cm to the nearest 10cm. The length of rope B is 200cm to the nearest 50cm. Work out the maximum possible total length of the two ropes.

Answer 6

350cm

Question 7

380 has been rounded to 2 significant figures. Give the error interval for it.

Answer 7

375/^x^385

Question 8

0.46 has been rounded to 2s.f. Give the error interval for it.

Answer 8

0.455/^y^0.465

Question 9

A bag of apples weighs 800g to the nearest 100g. A bag of potatoes weighs 1.5kg to the nearest 500g. What is the minimum possible weight of the apples and potatoes?

Answer 9

2000g