F.1 Maths Questions

1. 150balls are put into two boxes A and B. If the number of balls in box B is a multipleof that in box A , suggest two pairs of the numbers balls in boxes A and B.Factors of 150 : 1,2, 3, 5, 6, 10, 15, 25, 30, 75, 150
1x150, 2x75,3x50,5x30, 6x25, 10x15, 15x10, 2x6, 30x5, 50x3, 75x2, 150x1
If A = 1, B = 2x(150-1),
A+B
= 1+1x(150-1)
= 1+1x149
=1+149
=150
If A = 2, B = 2x(75-1),
A+B
= 2+2x(75-1)
= 2+2x74
=2+148
=150
……

2. Jennywants to send a parcel to her uncle. The postage is $38.2.She has some$1.4-stamps, $2.5-stamps. Suggest two ways paying the postage using these kindsof stamps.
1.4x13 + 2.5x8
= 18.2+20
=38.2

2008-08-06 16:21:27 補充：
1x150, 2x75,3x50,5x30, 6x25, 10x15

1. 10,140 or 50, 100
2. thirteen $1.4 stamps and eight $2.5 stamps (=$38.2, the only solution that can give 38.2)
or three $2.5 stamps and 22 $1.4 stamps (this will give $38.3)