Question 184850
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Use the formula for distance in terms of rate and time:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ d = rt]


If he returned 10 km at 30 km/hr then his time for the return trip must have been:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ t_d = \frac{10}{30} = \frac{1}{3}\ \text{hour}]


If his total travel time was 4 hours, then his walking time must be 4 hours minus his travel time in the car, so:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ t_w = 4 - \frac{1}{3} = \frac{12}{3} -\frac{1}{3} = \frac{11}{3}\ \text{hours}]


So his 10 km trip took *[tex \Large \frac{11}{3}\ \text{hours}]


Using the formula again, this time looking for rate in terms of distance and time:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ r = \frac{10}{ \frac{11}{3} }= 10 \left(\frac{3}{11}\right) = \frac{30}{11}\ \text{kph}]




John
*[tex \LARGE e^{i\pi} + 1 = 0]
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