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
2025-02-27
27
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/3974655.html
相关试题推荐
GivenapositivenumberN,whenNisroundedbyacertainmethod(forconvenienc
Acertainbrandofhousepaintmustbepurchasedeitherinquartsat$12eachor
Acertaintrucktravelingat55milesperhourgets4.5milespergallonofdies
Inacertainbox,thereare3timesasmanyredballsasblueballs.Whichofth
Howmanyhourswerebudgetedforacertainjob?(1)Thenumberofhoursbudgeted
Homeostasis,ananimal’smaintenanceofcertaininternalvariableswithinan
Neotropicalcoastalmangroveforestsareusually“zonal,”withcertainmangr
Governmentderegulationofthelong-distancetelephonebusinesshasresultedin
Acertainairportsecurityscannerdesignedtodetectexplosivesinluggagewill
Acertainmayorhasproposedafeeoffivedollarsperdayonprivatevehiclese
随机试题
IhavesetouttotravelfromtheAtlanticOceantothefoothillsoftheBolivia
温室效应greenhouseeffect
目钢网架的高空散拼法吊装,主要施工流程有:吊装机械的选择、()等。A.构件准备
重型地中海贫血患儿输血宜首选( )。A.洗涤红细胞 B.冰冻红细胞 C.少
按细度模数的大小,可将砂分为粗砂、中砂、细砂和特细砂。普通混凝土用砂宜选用为细度
A.回盲部 B.横结肠 C.空肠 D.直肠、乙状结肠 E.降结肠溃疡性结
一般资料:求助者,男性,35岁,本科学历,已婚。 案例介绍:求助者是军队干部,
依照《建设工程工程量清单计价规范》(GB50500—2013)的规定,承包人认为
某产品的预算产量为10000件,实际产量为9000件,实际发生固定制造费用180
一期梅毒的典型损害是A.掌跖角化斑 B.树胶肿 C.软下疳 D.扁平湿疣
最新回复
(
0
)