[求助]gwd-2-gmat-23

taiwan008

i can not search the following link, so plz help me :

the key i downloaded is A, but mine is C.

looks easy, but................. any trick?

Q23:

AMOUNT OF BACTERIA PRESENT

Time	Amount
1:00 P.M.	10.0 grams
4:00 P.M.	x grams
7:00 P.M.	14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A. 12.0

B. 12.1

C. 12.2

D. 12.3

E. 12.4

mikejia

10*(100%+x%)^2=14.4

so 10*(100%+x%)=?

then you can get the answer is C

mikejia

sorry , type wrong.

It is A

luoye1

理解比例谁是基数最重要

（12－10）/10=(12.4-12)/12

sportman

选Ａ

设每３个小时增长的比例是Ｘ，则有

10*(1+x)*(1+x)=14.4

解得X=0.2

所以在第一个3小时也就是4:00PM时the amount of bacteria 的数量是12.0grams

taiwan008

should be the misunderstanding of "increased by the same fraction "!

for me, it is really a good reminder.... be careful, never resume, never take for granted....

for this q:

assume the amount at 4pm is X:

according to the "increased by the same fraction";

(x-10)/10=(14.4-x)/x

x=12

tks....