To find the speed of the runner, we need to use the formula for speed:
\(Speed = \frac{Distance}{Time}\)
Here, the distance the runner covers is 750 meters, and the time taken is two and a half minutes (which is 2.5 minutes). First, we convert the time from minutes to hours to match the unit of speed in km/hr:
\(Time = 2.5 \, \text{minutes} = \frac{2.5}{60} \, \text{hours}\)
Now, let's convert the distance from meters to kilometers because the speed options provided are in km/hr:
\(Distance = 750 \, \text{meters} = 0.75 \, \text{kilometers}\)
Now apply these values to the speed formula:
\(Speed = \frac{0.75}{\frac{2.5}{60}}\)
Calculate the speed:
\(Speed = \frac{0.75 \times 60}{2.5} = \frac{45}{2.5} = 18 \, \text{km/hr}\)
Therefore, the speed of the runner is 18 km/hr, which is option A.
Conclusion: The runner's speed is 18 km/hr, accurately calculated using the given distance and time.
A box contains 16 red, 12 white, and 15 yellow identical marbles. A man picks one marble at a time without replacement. How many times must he pick a marble to be 100% certain of picking at least 3 white marbles?