Question

(a) Tom says that 1/5 + 7/20 = 8/25

Explain why he is wrong and show how to work out the correct answer.
(b) Show that 3/4 divided by 1 7/8 = 2/5
9. (a) Jadar is buying fencing to fence one side of his garden. He measures the length as 23cm to the nearest metre.
What is the largest possible true length of the garden?
(b) One post measures 180 cm truncated to 2 significant figures (Truncated means that rather than rounding, any digits after 2 significant figures are simply ignored

Answer 1

Explanation:

a)1/5+ 7/20

1.find the CM of both denominators

2.multiply both the denominator and the numerator using the CM

=(1/5)×20 +(7/20)

=20/100 +35/100

since you multiply

3.Now add both numerators ( don't add the denominators)

=the answer is 55/100

Answer 2

numerator = top part of the fraction

denominator = bottom part of the fraction

* means multiply

a.

you can only add the numerator when the denominator is the same

cant add the denominator

denominator has to be the same

1/5 = 4/20

4/20 + 7/20 = 11/20

b.

1 7/8 = 15/8

3/4 ÷ 15/8 =

3/4 * 8/15 =

24/60 = divide both top and bottom by 12 =

2/5