PSLE Irene baked a total of 50 large and small cakes in the ratio of 7 : 3. She decorated each cake with some grapes in the ratio of 7 : 3. She used a total of 160 grapes to decorate all the small cakes and 5 large cakes.
- How many small cakes did Irene bake?
- What was the number of grapes used to decorate all the small cakes?
- How many more grapes did Irene need to decorate the remaining large cakes?
(a)
Fraction of the cakes that were large ones =
77 + 3 =
710Number of large cakes
=
710 x 50
= 35
Number of small cakes
= 50 - 35
= 15
|
Large cakes |
Small cakes |
Total |
Number |
5 |
15 |
|
Value |
7 u |
3 u |
|
Total value |
35 u |
45 u |
80 u |
(b)
Number of grapes used to decorate 5 large cakes and 15 small cakes
= 35 u + 45 u
= 80 u
80 u = 160
1 u = 160 ÷ 80 = 2
Number of grapes used to decorate all the small cakes
= 45 u
= 45 x 2
= 90
(c)
Number of grapes to decorate one large cake
= 7 u
= 7 x 2
= 14
Number of remaining large cakes that were decorated yet
= 35 - 5
= 30
Number of more grapes that Irene needed to decorate the remaining large cakes
= 30 x 14
= 420
Answer(s): (a) 15; (b) 90; (c) 420