OG第二版里有一道例题,貌似不难,但我怎么也看不懂啊,数学当年好弱啊,能不能哪个好心的童鞋帮忙解释一下啊
题目如下:
Example 1.7.6: The monthly enrollment at a preschool decreased by 8% during one
month and increased by 6% during the next month. What was the cumulative percent
change for the two months?
原文解答:
Solution: If E is the enrollment before the first month, then the enrollment as a
result of the 8% decrease can be found by multiplying the base E by the decimal
equivalent of 100%−8%=92%, which is 0.92:
0.92E
The enrollment as a result of the second percent change—the 6% increase—can be
found by multiplying the new base 0.92E by the decimal equivalent of
100%+6%=106%, which is 1.06:
(1.06)(0.92)E=0.9752E
The percent equivalent of 0.9752 is 97.52%, which is 2.48% less than 100%. Thus,
the cumulative percent change in the enrollment for the two months is a 2.48% decrease.