PSLE
Fanny baked some biscuits. She gave ²₅ of the biscuits to her students and 70 to her friends. She was left with ⁷₂₀ of the biscuits. She packed these into 10 boxes. Some boxes contained 8 biscuits while the rest contained 11 biscuits.

1. How many biscuits were packed into the 10 boxes?
2. How many boxes contained 11 biscuits?

(a)
Fraction of the biscuits given to her friends
= 1 - ²₅ - ⁷₂₀

= 1 - ⁸₂₀ - ⁷₂₀
= ⁵₂₀

Number of biscuits that Fanny gave to her friends = 5 u

5 u = 70

1 u = 70 ÷ 5 = 14

Number of biscuits that were packed in 10 boxes
= 7 u
= 7 x 14
= 98

Number of biscuits that were packed in 10 boxes = 98

Boxes of 11	Biscuits	Boxes of 8	Biscuits	Total biscuits
10	110	0	0	110
9	99	1	8	107

If all the biscuits are packed in boxes of 11, the number of biscuits needed
= 10 x 11
= 110

Small difference
= 110 - 107
= 3

Big difference
= 110 - 98
= 12

Number of boxes of 8 biscuits 
= 12 ÷ 3
= 4

Number of boxes of 11 biscuits
= 10 - 4
= 6

Answer(s): (a) 98; (b) 6