2 snowplows can clear a road 12km x 4 m in 3 hours. How long will take for 10 snowplows to clear a road 2km x 12m.

My solution is 18 minutes but in book answer is 9 minutes. Am I wrong or there is error in book?

Guest Jan 24, 2021

#1**+1 **

You are right answer is 18 I also got 18

In first case area is 12000*4=48000m

2 person clear road at 3 hour so one person can do at 2*3 = 6 hour

Than 10 person can do this same work at 6/10= .6hour =36 minutes

In second case area is 2000*12=24000

So by logic time to do this work is 18 min

Guest Jan 24, 2021

#2**+1 **

2 snowplows can clear a road 12km x 4 m in 3 hours. How long will take for 10 snowplows to clear a road 2km x 12m.

** Hello Guest!**

\(N=W/t\)

\(N_{sp}=\dfrac{12km\cdot 4m}{2\cdot3h}\cdot \dfrac{1000m}{km}=8000m^2/h\)

\(t=\dfrac{W}{N_{sp}}\)

\(t=\dfrac{2km\cdot 12m}{10\cdot 8000m^2/h}\cdot \dfrac{1000m}{km} \)

\(t=0.3h\cdot\dfrac{60min}{h}=\color{blue}\ 18min\)

10 snowplows clear a road of 2km x 12m in 18min.

You're right.

!

asinus Jan 24, 2021

#3**+2 **

2 snowplows can clear a road 12km x 4 m in 3 hours. How long will take for 10 snowplows to clear a road 2km x 12m.

My solution is 18 minutes but in book answer is 9 minutes. Am I wrong or there is error in book?

Omi67 Jan 24, 2021

#8**0 **

Wait I get 9 minutes Why am I getting 9 minutes when everyone else is getting 18 minutes

I must have made a mistake

Guest Jan 24, 2021

#10**0 **

You made a mistake its 18 minutes I just rechecked my work. Its .3 hours that is 18 minutes.

Guest Jan 24, 2021

#11**0 **

Oh I did make a mistake. Its a good thing everyone is checking its easy to get wrong!!!

Guest Jan 24, 2021