(a) The distance d , in feet, required for avehicle traveling at r mi/h to come
ID: 3092417 • Letter: #
Question
(a) The distance d, in feet, required for avehicle traveling at r mi/h to come to a stop is givenapproximately by d = 0.05r2 + r. If anautomobile in a 55 mi/h speed zone required 240 ft to stop, was itsspeed within the legal limit? (b) A farmer plans to use 21 m of fencing to enclose arectangular pen having area 55 m2. Only three sides ofthe pen need fencing because part of an existing wall will form thefourth side. Find the dimensions of the pen. (a) The distance d, in feet, required for avehicle traveling at r mi/h to come to a stop is givenapproximately by d = 0.05r2 + r. If anautomobile in a 55 mi/h speed zone required 240 ft to stop, was itsspeed within the legal limit? (b) A farmer plans to use 21 m of fencing to enclose arectangular pen having area 55 m2. Only three sides ofthe pen need fencing because part of an existing wall will form thefourth side. Find the dimensions of the pen.Explanation / Answer
A)from the problems you can conclude that:
240=.05r²+r
Plug that into your graphing calculator as
Y=240
Y=.05r²+r
The x value at the point of intersection of the two graphs showsthe driver’s speed to be 60 miles per hour.
B)
you can set up a system of equation:
have x equal the side that runs perpendicular to the wall and havey run parallel to the wall.
________y _________
| |
| |
x | | x
| |
______|__________________|___________________
Wall
Then set up the equations according to the problem
2x+y=21
(x)(y)=55
When you eliminate y by substitution you get x=5
Plug that into either equation and you get that y=11
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