gwd-9-24

knight9514

Q24:

A certain fruit stand sold apples for $0.70 each and bananas for $0.50 each. If a customer

purchased both apples and bananas from the stand for a total of $6.30, what total number

of apples and bananas did the customer purchase?

A. 10

B. 11

C. 12

D. 13

E. 14

已经晕了，不是买9个苹果就6.3块了么？7只有乘以9后个位才会是3，苹果和香蕉一起买怎么也买不出6.3块啊？

sammen

0.7*4+0.5*7=6.3

daoying

我拼出来是4个苹果+7个香蕉=4*0.7+7*0.5=6.3

但是答案不是11啊,不懂!

himba

apple(0.7)	banana(0.5)		banana(0.5)Apple
1x0.7	5.6/0.5=I , no		1x0.5	5.8/0.7, no
2x0.7	4.9/0.5=I, no		2x0.5	5.3/0.7, no
3x0.7	4.2/0.5, no		3x0.5	4.8/0.7, no
4x0.7	3.5/0.5, yes		4x0.5	4.3/0.7, no
5x0.7	2.8/0.5, no		5x0.5	3.8/0.7, no
6x0.7	2.1/0.5, no		6x0.5	3.3/0.7, no
7x0.7	1.4/0.5, no		7x0.5	2.8/0.7, yes
8x0.7	0.7/0.5, no		8x0.5	2.3/0.7, no
9x0.7	yes,		9x0.5	1.8/0.7,no
			10x0.5	1.3/0.7, no
			11x0.5	0.8/0.7, no

So, 11 is the only possible answer.

poorleafs

0.7x+0.5y=0.63 =>x=(0.63-0.5y)/0.7=9-(5y)/7 => y=7, x=4.