PSLE Jen baked a total of 40 large and small cakes in the ratio of 5 : 3. She decorated each cake with some grapes in the ratio of 3 : 2. She used a total of 459 grapes to decorate all the small cakes and 7 large cakes.
- How many small cakes did Jen bake?
- What was the number of grapes used to decorate all the small cakes?
- How many more grapes did Jen need to decorate the remaining large cakes?
(a)
Fraction of the cakes that were large ones =
55 + 3 =
58Number of large cakes
=
58 x 40
= 25
Number of small cakes
= 40 - 25
= 15
|
Large cakes |
Small cakes |
Total |
Number |
7 |
15 |
|
Value |
3 u |
2 u |
|
Total value |
21 u |
30 u |
51 u |
(b)
Number of grapes used to decorate 7 large cakes and 15 small cakes
= 21 u + 30 u
= 51 u
51 u = 459
1 u = 459 ÷ 51 = 9
Number of grapes used to decorate all the small cakes
= 30 u
= 30 x 9
= 270
(c)
Number of grapes to decorate one large cake
= 3 u
= 3 x 9
= 27
Number of remaining large cakes that were decorated yet
= 25 - 7
= 18
Number of more grapes that Jen needed to decorate the remaining large cakes
= 18 x 27
= 486
Answer(s): (a) 15; (b) 270; (c) 486