PSLE
Lucy baked a total of 42 large and small cakes in the ratio of 4 : 3. She decorated each cake with some cherries in the ratio of 7 : 4. She used a total of 242 cherries to decorate all the small cakes and 7 large cakes.

1. How many small cakes did Lucy bake?
2. What was the number of cherries used to decorate all the small cakes?
3. How many more cherries did Lucy need to decorate the remaining large cakes?

(a)
Fraction of the cakes that were large ones = ⁴_{4 + 3} = ⁴₇

Number of large cakes
= ⁴₇ x 42
= 24

Number of small cakes
= 42 - 24
= 18

	Large cakes	Small cakes	Total
Number	7	18
Value	7 u	4 u
Total value	49 u	72 u	121 u

(b)
Number of cherries used to decorate 7 large cakes and 18 small cakes
= 49 u + 72 u
= 121 u

121 u = 242

1 u = 242 ÷ 121 = 2

Number of cherries used to decorate all the small cakes
= 72 u
= 72 x 2
= 144

(c)
Number of cherries to decorate one large cake
= 7 u
= 7 x 2
= 14

Number of remaining large cakes that were decorated yet
= 24 - 7
= 17

Number of more cherries that Lucy needed to decorate the remaining large cakes
= 17 x 14
= 238

Answer(s): (a) 18; (b) 144; (c) 238