E: Jerry's speed
M: Jim's speed
First, Jerry gives Jim a start of 200m and beats him by 30 secondsStart Finish line
A------------------B-----------------------C-------------------Z
[___200m____] [__Jim's 30s___]
[___________________2000m_________________]
(i) Jim starts at B
(ii) By the time Jerry at Z, Jim is at C and must run 30s more to reach Z
\(\frac{2000}{E} = \frac{1800}{M} - 30\)
Next, Jerry gives Jim a start of 3mins and is beaten by 1000mStart Finish line
A--------------------H-----------K-------------------------------Z
[__Jim's 180s__] [________1000m______]
[_____________________2000m_________________]
By the time Jim at Z
+) Distance run by Jerry: 1000m
+) Distance run by Jim: 2000m
However, Jim runs before Jerry 180s, Jerry is at K
\(\frac{1000}{E} = \frac{2000}{M}- 180\)
So we have\(\frac{2000}{E} = \frac{1800}{M} - 30\)
\(\frac{1000}{E} = \frac{2000}{M}- 180\)
=> \(\frac{900}{M} - 15 = \frac{2000}{M} - 180\)
=> \(\frac{1100}{M} = 165\)
=> \(\frac{100}{M} = 15\)
=> \(M = \frac{100}{15} = \frac{20}{3} (m/s)\)
\(\frac{20m}{3s} = \frac{20 m}{3 s} * \frac{60 s}{1 min} = \frac{400 m}{ 1 min}\)
=> M = 400 m/s
=> time for M to finish the race: \(\frac{2000}{400} = 5\)min