PSLE Sarah baked a total of 44 large and small cakes in the ratio of 7 : 4. She decorated each cake with some raspberries in the ratio of 7 : 3. She used a total of 485 raspberries to decorate all the small cakes and 7 large cakes.
- How many small cakes did Sarah bake?
- What was the number of raspberries used to decorate all the small cakes?
- How many more raspberries did Sarah need to decorate the remaining large cakes?
(a)
Fraction of the cakes that were large ones =
77 + 4 =
711Number of large cakes
=
711 x 44
= 28
Number of small cakes
= 44 - 28
= 16
|
Large cakes |
Small cakes |
Total |
Number |
7 |
16 |
|
Value |
7 u |
3 u |
|
Total value |
49 u |
48 u |
97 u |
(b)
Number of raspberries used to decorate 7 large cakes and 16 small cakes
= 49 u + 48 u
= 97 u
97 u = 485
1 u = 485 ÷ 97 = 5
Number of raspberries used to decorate all the small cakes
= 48 u
= 48 x 5
= 240
(c)
Number of raspberries to decorate one large cake
= 7 u
= 7 x 5
= 35
Number of remaining large cakes that were decorated yet
= 28 - 7
= 21
Number of more raspberries that Sarah needed to decorate the remaining large cakes
= 21 x 35
= 735
Answer(s): (a) 16; (b) 240; (c) 735