While Janet is shopping, she comes along this sign that says, "SALE! All jeans on this rack are 1/3 off the original price (original price $29.99). Which of the following expressions can be used to estimate the total discount on a pair of jeans? A. 0.033 x $30 B. 0.33 x $30 C. 1.3 x $30 D. 33.3 x $30

Question

phi · Answer

they rounded 29.99 to 30

can you rule out any of the choices as wrong?

phi · Answer

the total discount is the amount taken off of the 30
you would guess the discount is bigger than 0 and less than 30 (in other words, they still charge something for the jeans)

anonymous · Answer

yes but i dont know how to solve it

phi · Answer

First, which choices do you think are wrong?

anonymous · Answer

im going with C. and maybe A or D

phi · Answer

do you understand what discount means ?

anonymous · Answer

yes

phi · Answer

when they say,  1 /3 off, do you think that means 30 off (making the price 0?

phi · Answer

D. 33.3 x $30

is a choice for the discount.   if you multiply that out you get a huge number (much bigger than 30) and that is supposed to be the amount taken off the price.   It's way too big.

phi · Answer

C. 1.3 x $30 
if you multiply that out you still get a discount bigger than 30.
still too big.

so if you were totally lost, you should be able to get down to 50-50 chance
either A or B

phi · Answer

But here is how to do it
the discount is 1 /3 of 30
that means  figure out 1/ 3 times 30
you get   1 /3 * 30 = 10

which choice, when you multiply it out gives something close to 10?

phi · Answer

and you need to check only A and B

anonymous · Answer

Ok thanks for your help.

phi · Answer

the other way to do this is change 1 /3 do a decimal
divide 3 into 1 to get 0.333...

so 0.3333...* 30 is the answer
or, roughly (because we are estimating)
0.33 * 30