nalinnair wrote:

To order certain plants from a catalog, it costs $3.00 per plant, plus a 5 percent sales tax, plus $6.95 for shipping and handling regardless of the number of plants ordered. If Company C ordered these plants from the catalog at the total cost of $69.95, how many plants did Company C order?

A. 22

B. 21

C. 20

D. 19

E. 18

You do not have to do any calculations if you understand the propertiies of number thrown by Q...

A constant amount is 6.95 and Toatl is 69.95...

so variable price dependent on # of plants = 69.95-6.95 = 63...

where as cost of ONE plant is NON_INTEGER 3+ 5% of 3, total is an integer.....

so # of plants has to be multiple of 10 to give an integer..

ONLY 20 is possible

C...

METHOD...

cost of ONE plant =\(3 + 3*0.05 = 3.15...\)

let the # of plants be p..

so \(3.15p+6.95=69.95................ 3.15p=63......................p= \frac{63}{3.15} = \frac{6300}{315}= 20\)

C

_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372

2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html

GMAT Expert