Pat travels 70 miles on her milk route, and Bob travels 75 miles on his route. Pat travels 5 miles per hour slower than Bob, and her route takes her one half hour longer than Bob's. How fast is each one traveling?

1 Answer
Nov 21, 2017

V_(bob)=16 2/3 (m i l e s)/(h o u r)Vbob=1623mileshour

V_(pat)=11 2/3 (m i l e s)/(h o u r)Vpat=1123mileshour

Explanation:

T*V=STV=S
V=velocity
T=time
S=route


S_p=70Sp=70
S_b=75Sb=75
V_p=V_b-5Vp=Vb5
T_p=T_b+1.5Tp=Tb+1.5

T_p*V_p=S_pTpVp=Sp
T_b*V_b=S_bTbVb=Sb
=>
(T_b+1.5)*(V_b-5)=70(Tb+1.5)(Vb5)=70
T_b*V_b=75TbVb=75

I want to find V_bVb and V_pVp:
=>
(T_b+1.5)*(V_b-5)=70(Tb+1.5)(Vb5)=70
T_b=75/V_bTb=75Vb

=>
(75/V_b+1.5)*(V_b-5)=70(75Vb+1.5)(Vb5)=70

Let V_b=xVb=x
=> (75/x+1.5)*(x-5)=70(75x+1.5)(x5)=70
=> 75-375/x+1.5x-7.5=7075375x+1.5x7.5=70
=> -375/x+1.5x-2.5=0375x+1.5x2.5=0
=> -375+1.5x^2-2.5x=0375+1.5x22.5x=0
=> 1.5x^2-2.5x-375=01.5x22.5x375=0
=>
x_(1,2)=(2.5+-sqrt((-2.5)^2-4*(1.5)*(-375)))/(2*1.5)x1,2=2.5±(2.5)24(1.5)(375)21.5
=...=
x_1=50/3=16 2/3
x_2=-15

Velocity cannot be negative, so:
=>
x=16 2/3=V_b
=>
V_p=V_b-5=16 2/3-5=11 2/3