问几道GRE的数学题，请大家帮帮忙，快考试了 谢谢 达人们 不胜感激 ！！！

Question

1.On a trip Marie drove 200miles in 5 hours using gasoline that cost her 1.49 dollar per gallon
请比较大小：
Marrie's average speed for the trip in miles per hour
和 Marie's gas mileage for the trip in miles per galon

2.A retail business has determined that its net income.in terms of x, the number of the items sold, is given by the expression x的平方加上x减去380
比较大小the number of items that must be sold for the net income to be zero 和 10

3.S is the set of all fractions of the form n/(n+1),where n is a positive integer less than 20
比较大小 the product of all the fractions that are in S 和 1/20

4.A decrease in the number of scales personnel in Company K to 85 percent of the original sales force resulted in a decrease of 500 in the number of monthly sales.
比较大小 The percent decrease in the number of Company K's monthly sales和 The percent decrease in the number of Company K's sales personnel.

5.是一道图表题 是黄书section59 上第19题

谢谢 达人们 不胜感激

Answer 1

第一道题：没法比较吧？选D
第二道题：原式分解得(x+20)*(x-19)=0，所以x=19，大于10，所以选A
第三道题：the product of all the fractions that are in S为1/2*2/3*…18/19*19/20=1/20，等于右边。所以选C
第四道题：条件不足吧？选D
第五道题：选D。工资数目应该介于23.0-24.2之间。如果按照每年增加0.5千元来计算，第5年应该为22.6，但是因为题目已经说了第5年增加的是0.9，所以修正后为23.0；同理，如果每年增加0.9，则第五年为20.1+0.9*5=24.6，修正后为24.2。