Unit 4
4 marks · EasyA music store holds a sale and reduces the price of a guitar by 20%. The original price was $180.
Calculate the sale price of the guitar after the 20% reduction.
A formula used in the store is , where is the current price, is the original price, and is the discount. Use this formula to find the value of in this case.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 144 dollars
(b) 36 dollars
Common mistakes: Incorrectly finding 20% of the original price but not subtracting; Not using the formula correctly; using original instead of discount
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Calculates 20% of $180 or finds multiplying factor (0.8 or 1-0.2)
A1 (a) · 1 mark · Finds final sale price as $144
M2 (b) · 1 mark · Substitutes values into
A2 (b) · 1 mark · Finds correct discount value $36
Worked solution
a) 20% of 180 = . Sale price = 180 - 36 = $144.
b) Use , with , : , so .