69. Mr. Zhang ordered to store a commodity, priced 100 yuan each, ordered a total of 60. Zhang said the store manager, "If you are willing to reduce the price, on sale for one dollar, the more I ordered 3", store manager figured, if up to 4%, due to the multi-ordered Mr. Zhang, the original can still get as much gross profit, what the cost of this product is:
A.76
B. 80
C. 75
D. 85
Answers: A
Answer: The cost of this product set is x dollars, then in accordance with the original price (100 yuan) to sell, then the profit per item is 100-x, then 60 is: 60 * (100 -x), this is the original total profit.
Under manager Well, the decision up to 4%: then the new price per item is: 100 * (1-4%) = 96 yuan, the profit that each piece is: 96 - x
Price reduction: 100% = 4 * 4 million, in accordance with one per Clearance, buy three, the number of pieces of merchandise are so many Sell: 3 * 4 = 12, sold a total of: 60 + 12 = 72
Then the total profit after adjustment is: (96 - x) * 72.
The total profit before and after the casual working, adjustment is the same, there are:
60 * (100 -x) = 72 * (96-x)
Left and right sides are divided by 12, to give: 5 * (100 -x) = 6 * (96-x)
Both sides are deployed: 500 - 5x = 576 - 6x
x = 76
That is the original cost of goods is 76 yuan
70. In response to the call of environmental protection, a battery manufacturer promises: with three old batteries can change a new battery, Li has 21 old batteries, may I ask him a total return () block new battery.
A. 7
B. 9
C. 10
D. 11
Reference answer: C
Answer: This question is buried in the pit, and if it is 21/3 = 7 (chose A), is to step on the pit.
21 with old batteries, new batteries can change 7 (+7) immediately. However, this new seven batteries run out, can also change, and can change a new battery 7/3 = 2 (+2), there remains an old battery.
Two new batteries run out, Li will have a hand of the old battery 3 (the remaining one is applied before the old batteries), which can also install a new one (+1).
This new battery ran out, Mike only have an old battery, enough to change a new battery.
Therefore: Li changed Total: 7 + 2 + 1 = 10 cells.