pls help exam in 2 days

during a sale, a clothing store sold each shirt at a price of $15 and each sweater at $25. did the store sell more sweaters than shirts during the sales.
1. the average (arithmetic mean) of the prices of all the shirts ans sweaters that the store sold during the sale was $21

avg of 25 & 15 is 20 i.e if the store sold an equal nos of shirts & sweaters then the avg price would be 20$, so if avg is 21, then nos of sweaters sold is more than shirts SUFF.

2. the total of the prices of all the shirts and sweaters that the store sold during the sale was $420

i.e 15a + 25b = 420

I dont know abt any standard approach to this one

but I used this one


highest multiple of 25 that is closest to 420 is 16 ie 400

but in that case 20 is left out
next lower multiple is 375 (15) leving 45 (muliple of 15) so

now of sweaters can be more than the nos shirts

now if we try this with 15 we have

15 * 28 = 420 , since stmt 2 explicity mentions that both were sold, we can move down to the lower multiples

here staraight away we can say that 75 is a common multiples of 15 & 25

so (420 -75)/15 shirts we sold & 3 sweaters

so this stmt is INSUFF

A

Hi

I did this slightly diff

I just used the equation -

15x + 25y = 21(x+y)

when we solve we get the ratio of y:x = 3/2

so we know they sold more sweaters than shirts