PSLE Erika baked a total of 20 large and small cakes in the ratio of 7 : 3. She decorated each cake with some grapes in the ratio of 3 : 2. She used a total of 231 grapes to decorate all the small cakes and 7 large cakes.
- How many small cakes did Erika bake?
- What was the number of grapes used to decorate all the small cakes?
- How many more grapes did Erika need to decorate the remaining large cakes?
(a)
Fraction of the cakes that were large ones =
77 + 3 =
710Number of large cakes
=
710 x 20
= 14
Number of small cakes
= 20 - 14
= 6
|
Large cakes |
Small cakes |
Total |
Number |
7 |
6 |
|
Value |
3 u |
2 u |
|
Total value |
21 u |
12 u |
33 u |
(b)
Number of grapes used to decorate 7 large cakes and 6 small cakes
= 21 u + 12 u
= 33 u
33 u = 231
1 u = 231 ÷ 33 = 7
Number of grapes used to decorate all the small cakes
= 12 u
= 12 x 7
= 84
(c)
Number of grapes to decorate one large cake
= 3 u
= 3 x 7
= 21
Number of remaining large cakes that were decorated yet
= 14 - 7
= 7
Number of more grapes that Erika needed to decorate the remaining large cakes
= 7 x 21
= 147
Answer(s): (a) 6; (b) 84; (c) 147