PSLE
Jen baked a total of 21 large and small cakes in the ratio of 5 : 2. She decorated each cake with some raspberries in the ratio of 7 : 3. She used a total of 322 raspberries to decorate all the small cakes and 4 large cakes.

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

(a)
Fraction of the cakes that were large ones = ⁵_{5 + 2} = ⁵₇

Number of large cakes
= ⁵₇ x 21
= 15

Number of small cakes
= 21 - 15
= 6

	Large cakes	Small cakes	Total
Number	4	6
Value	7 u	3 u
Total value	28 u	18 u	46 u

(b)
Number of raspberries used to decorate 4 large cakes and 6 small cakes
= 28 u + 18 u
= 46 u

46 u = 322

1 u = 322 ÷ 46 = 7

Number of raspberries used to decorate all the small cakes
= 18 u
= 18 x 7
= 126

(c)
Number of raspberries to decorate one large cake
= 7 u
= 7 x 7
= 49

Number of remaining large cakes that were decorated yet
= 15 - 4
= 11

Number of more raspberries that Jen needed to decorate the remaining large cakes
= 11 x 49
= 539

Answer(s): (a) 6; (b) 126; (c) 539