Y directly proportional to WX and inversely to Z.
Y=k(WX)/Z
Where k is the constant of proportionality.
So, the first thing is to find the value of this constant.
k = YZ/WX
= (32×3)/(6×20)
= 96/120
= 0.8
The <span>equation that models the relationship will be;
Y = 0.8(WX/Z)</span>
Ann wants to choose from two telephone plans. Plan A involves a fixed charge of $10 per month and call charges at $0.10 per minute. Plan B involves a fixed charge of $15 per month and call charges at $0.08 per minute.
Plan A $10 + .10/minute
Plan B $15 + .08/minute
If 250 minutes are used:
Plan A: $10+$25=$35
Plan B: $15+$20=$35
If 400 minutes are used:
Plan A: $10+$40=$50
Plan B: $15+$32=$47
B is the correct answer. How to test it:
Plan A: $10+(.10*249 minutes)
$10+$24.9=$34.9
Plan B: $15+(.08*249 minutes)
$15+$19.92=$34.92
Plan A < Plan B if less than 250 minutes are used.
Speed=distance/time
suppose the distance of the first day is d, and the time is t
distance of the second day: d+0.17d=1.17d
time of the second day: t+0.2t=1.2t
speed of the second day: 1.17d/1.2t=0.975(d/t)=(1-0.025)(d/t)
so the speed of the second day is 2.5% slower than the first day.
