PSLE Erika baked a total of 21 large and small cakes in the ratio of 4 : 3. She decorated each cake with some grapes in the ratio of 8 : 5. She used a total of 436 grapes to decorate all the small cakes and 8 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 =
44 + 3 =
47Number of large cakes
=
47 x 21
= 12
Number of small cakes
= 21 - 12
= 9
|
Large cakes |
Small cakes |
Total |
Number |
8 |
9 |
|
Value |
8 u |
5 u |
|
Total value |
64 u |
45 u |
109 u |
(b)
Number of grapes used to decorate 8 large cakes and 9 small cakes
= 64 u + 45 u
= 109 u
109 u = 436
1 u = 436 ÷ 109 = 4
Number of grapes used to decorate all the small cakes
= 45 u
= 45 x 4
= 180
(c)
Number of grapes to decorate one large cake
= 8 u
= 8 x 4
= 32
Number of remaining large cakes that were decorated yet
= 12 - 8
= 4
Number of more grapes that Erika needed to decorate the remaining large cakes
= 4 x 32
= 128
Answer(s): (a) 9; (b) 180; (c) 128