A man wants to spray the entire surface of the Earth (including the oceans) with a new weed killer. If it takes him 10 seconds to spray 1m^2, how long will it take to spray the whole world? ( Radius of the Earth = 6370km; ignore leap years)

Question

mathstudent55 · Answer

First, find the formula for the surface area of a sphere, and using the Earth's radius find the surface area of the Earth.

mathstudent55 · Answer

Notice you are given the radius in km, but you need the area in m^2, so convert the radius to m to find the area in m^2.

sarkinyy · Answer

I did what you said and then multiplied by 10 sec but I don't get the answer from the Marc scheme

jiteshmeghwal9 · Answer

Surface area =4$\pi r^2$ where r is radius of earth.

time taken to spray 1m^2 ----> 10 sec
time taken to spray 4$\pi r^2$-----> 10 $\times$ $4 \pi r^2$

vondylan · Answer

http://openstudy.com/study#/updates/57e2a6f5e4b0e5e04a810d92

jiteshmeghwal9 · Answer

the time will come in seconds .

If u want  may convert seconds into years.
1 year = 3153600 sec

sarkinyy · Answer

Ok thx I had to convert it in years