Common error

Likely miscalculation

Likely reason

a) i)
b) i)
c) i)
d) i)

1/3
4/5
4
2/5

Original length ¸ enlarged length.

Reverses order of division.

c) i)

G 1/4, G 4

Adds a negative sign to answer because it is a reduction.

a) i)
a) ii)
b) i)
b) ii)
c) i)
d) i)
d) ii)
d) ii)

30
50
11
31
57
45
105
15

Enlarged length - original length.

Subtracts instead of divides two lengths, then adds (or subtracts) this difference.

c) ii)

48

12 × 4

Multiplies by 4 instead of 1/4 .

d) ii)
d) ii)

40
150

20 × 2
75 × 2

Doubles side to be enlarged without calculating scale factor.