请教两道困扰我的数学题，谢谢！

RuiGMAT

1.  Amount of bacteria present

Time       amount

1pm        10.0 grams

4pm        x grams

7pm        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 4pm?

A 12.0

B 12.1

C 12.2

D 12.3

E 12.4

答案是A，我觉得是不是答案错了。我觉得是C。

2. In town X, 64 percent of the population are employed, and 48 percent of the population are employed males. What percent of the employed people in Town X are females?

 

A 16%

B 25%

C 32%

D 40%

D 52%

答案是B，我不懂。

恳请明白的朋友指点一下，谢谢！

woklovepp

1 应该是a，题目说每3个小时增加的比例相同

就是：(x-10)/10=(14.4-x)/x

解出：x=12

RuiGMAT

哦，原来是这样，我恍然大悟。

哈哈，谢谢啦！

homowing

2.

0.64*P--> Employed

0.48*P--〉male(Employed)

推出0.16*P-->female(Employed)

推出female(Employed)/Employed= (0.16*P)/(0.64*P)=0.25

RuiGMAT

又明白一题，谢谢！