**Step-by-step Answer:**

Very tricky question where we have to pay attention to units.

Total distance = D = 50 m

Total speed = S = 1+2 = 3 miles per hour

When they run towards each other for a given distance, the solution is given by

time = total distance / total speed

= 50 metres / (2+1) miles per hour.

= 50 metres / 3 miles per hour

We know that 1 inch = 2.54 cm exactly, so

D3= distance of three miles

= 3 miles

= 3 miles * 1760 yards /mile

= 3*1760 yards * 36 inches per yard

= 3*1760*36 inches * 2.54 cm / inch

= 3*1760*36*2.54 cm

= 3*1760*36*2.54 cm * (1/100) m/cm

= 3*1760*36*2.54/100 metres

The total speed is therefore

S = D/3600 seconds

= 3*1760*36*2.54/100 / 3600

= 1.34112 m/s (exactly)

Therefore time before they meet is

Time = Distance / total speed

= D / S

= 50 metres / S m/s

= 50 / 1.34112 seconds

= 37.28 seconds (to the hundredth of a second)