首页
登录
职称英语
When a certain stretch of highway was rebuilt and straightened,the distance alon
When a certain stretch of highway was rebuilt and straightened,the distance alon
游客
2024-01-13
48
管理
问题
When a certain stretch of highway was rebuilt and straightened,the distance along the stretch was decreased by 20 percent and the speed limit was increased by 25 percent.By what percent was the driving time along this stretch reduced for a person who always drives at the speed limit?
选项
A、
B、
C、
D、
E、
答案
B
解析
Let D and r be the distance and speed limit, respectively, along the stretch of highway before it was rebuilt. Then, the distance and speed limit along the stretch of highway after it was rebuilt are given by 0.8D and 1.25r. It follows that the percent reduction in time is
Alternatively, it helps to use actual numbers when calculating percent change, with 100 being the most mathematically convenient number to use. For this problem, set the speed limit at 100 miles per hour and the distance at 100 miles.
A 20 percent decrease in distance makes the new distance 80 miles. A 25 percent increase in speed limit makes the new speed limit 125 miles per hour, which, of course, is unrealistic, but very convenient to work with. Then, the new time distance/rate is 80/125 hours, The percent change in time is
The correct answer is B.
转载请注明原文地址:https://tihaiku.com/zcyy/3360093.html
相关试题推荐
Ofcourseacertainamountofdependenceonothersisnotonlygood,butneces
WINK,Inc.followsacertainprocedurethatrequirestwotaskstobefinishedin
Closingpricesforacertainstockwererecordedeachdayforaweekinthetabl
Acertaintirecompanycanproducetiresatacostof$22,500perbatchplus$9
Atypeofextra-largeSUVaverages12.2milespergallon(mpg)onthehighway,b
Acertainprosthodontistspecializesinimplantinggoldandsilverteethinhis
Inacertainconservativemutualfund,70percentofthemoneyisinvestedinbo
Inacertaingrowthfund,3/5oftheinvestmentcapitalisinvestedinstocks,a
Acertaintruckuses18gallonsofdieselfuelintraveling270miles.Inorder
Inacertainflowershop,whichstocksfourtypesofflowers,thereare-asman
随机试题
[img]2012q1/ct_eilm_eillist_0399_20121[/img][br][originaltext]IfI’vepersuad
A.sensibleB.comprehensiveC.readilyD.incaseE.sensitiveF.passi
A.removeB.judgeC.intelligenceD.indicate
Thomaswasarealfriend,forheadvisedmeaswellas(help)____________mewith
[originaltext]Attheendofeveryyear,U.S.weatherresearcherslookback
Word安装完毕第一次启动时,屏幕上的缺省工具栏是()。A.格式 B.常用
关于紧急救护,以下说法不正确的是A.遇有患者病情危急时,护士应立即通知医师 B
期货结算机构的职能有()。A.监控期货交易所财务风险 B.结算期货交易盈亏
下列房产中免征房产税的是()。A.自收自支事业单位向职工出租的单位自有住房
债务人或者第三人有权处分的下列权利中,可以质押的是()。A.建设用地使用权
最新回复
(
0
)