The number of students that sat the Physics exam in 2013 was 8400. This was an increase of 5% on the number that sat the Physics exam in 2012. How many students sat the Physics exam in 2012?
____ 100 = 1 + 5
1⋅05 N = 8400 N = 8400
____ 100 = 1·05
N is the number of students that sat the Physics exam in 2012:
_____ 1·05 = 8000
or
The percentage that sat the Physics exam in 2012 is 100%. Therefore, the percentage that sat the Physics exam in 2013 is 105%, which is 8400 students.
105% = 8400 1% = 8400
_____ 105
100% = 8400 _____
EXAMPLE 4
The price of a house in 2013 was 43% less than its price in 2008. If the price in 2013 was €342 000, what was the price in 2008?
Solution 1 – r
____ 100 = 1 – 43
____ 100 = 0·57
p was the price in 2008: 0·57p = 342 000
p = 342 000 _______
0· 57 = €600 000 or
If 100% was the price in 2008: Price in 2013 = 57% = 342 000
1% = 342 000 _______
57
100% = 342 000 _______
57 EXERCISE 6
1. Write the following as percentages: (a) 0·5 (b) 0·25 (c) 0·6 (d) 0·48 (e) 1·6
(f) 7·65 (g) 0·23 (h) 2 (i) 0·7 (j) 0·18
2. Write the following as decimals and fractions in their lowest form:
