# Thread: working out the percentage!

1. ## working out the percentage!

hi this is my question:
In a sale the price of a digital radio decreases from £75 to £66.
work out the percentage decrease in price.

im not sure but would it be 72.53%?? if that is wrong can anyone help me please?

2. Originally Posted by andyboy179
hi this is my question:
In a sale the price of a digital radio decreases from £75 to £66.
work out the percentage decrease in price.

im not sure but would it be 72.53%?? if that is wrong can anyone help me please?

The "decrease" in sterling is 75-66=£9

This is a decrease of £9 from £75,

so you must express this decrease as a percentage of £75

The fraction is $\displaystyle \frac{9}{75}$

A percentage is the fraction multiplied by 100

(remember $\displaystyle \frac{1}{2}$ is 50%).

How did you calculate 72.53% ?

3. at school it is called the £1 method, we start with £1 and with this question is it decrease by 9 so it would be x0.91 then you use the starting price and / by 0.91 = 82%
(i messed up the first answer i put which was 72.53%)

4. Originally Posted by andyboy179
at school it is called the £1 method, we start with £1 and with this question is it decrease by 9 so it would be x0.91 then you use the starting price and / by 0.91 = 82%
(i messed up the first answer i put which was 72.53%)

75 decreases by 9

$\displaystyle \frac{75}{100}=0.75$

So 100 would decrease by $\displaystyle 9\left(\frac{1}{0.75}\right)=\frac{9}{0.75}=12$

100 would decrease by more so you put the 1 on top of the fraction and 0.75 underneath.

That's a 12% decrease