Calculating percentage and converting? Too long, so I put it in the description :)

Question

Jenna sells Lemonade for $10 per glass. She offers a 20% discount. The price is recalculated then she offers an additional 10% discount. Aidan wants to match her deal by offering a single discount percentage . What should his discount percentage be?

Answer 1

First find the price of Jenna's lemonade.

 

1st discount

.2×10=$2.00 off

 

10.00-2.00=

$8.00

 

2nd discount

8.00×.1=$.80

 

8.00-.80=

Jenna's final lemonade price: $7.20

 

Figure out Aidan's discount to get the lemonade from $10.00 to $7.20.

 

Use a proportion.

 

7.20/10.00=X/100

 

Solve for X by cross multiplying

 

720=10X

X=72%

 

72% is how much is paid, not the discount. To get the discount percentage you have to subtract 72% from 100%.

 

100-72=28%

Final answer is 28%.

Answer 2

( 100 - 20) % *  ($10)= 0.8 ($10)=8    first discount  / first discount sells it

 

 ( 100 -90) )% ( $8) = 0.90 ( $80) = 7.2

 

   After first discount sells it for 80% of the original price

   After 2nd discount sells it for 90% of the first discounted .

 

   So in one statement :

 

   0.90 x 0.80 = .72     72% percent of original price.

 

      1 - 0.72 = .28     28% discounted price.

Answer 3

This problem can be done and should be done in a much simpler way.

 

After the two discounts, the remaining part is .8*.9 = .72

So, the equivalent discount percentage is 1-.72 = 28%.

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Attn: Focus on the remaining part each time: 20% discount means 80% remaining. 10% discounts means 90% remaining.

 

 

Answer 4

here's a different approach

$10 per glass

20 % discount means the price is 80 % of $10 or $8

another 10 % discount means the price is now 90 % of $8 or $7.20

now it is a simple matter of finding the percent of decrease from $10 to $7.20

$10.00-$7.20=$2.80

now put $2.80 over $10.00 and change to a percent

2.8/10=28/100=28 %

Aidan must decrease his price by 28 %

another approach:what percent of $10 is $7.20 ?

7.2/10=72/100=72 %

Aiden must charge only 72 % of $10, which equals a discount of 28 %