Final answer:
Mario rides his bike at a rate of 6 feet per second by dividing the length of a block (300 feet) by the time taken to pass one block (50 seconds).
Step-by-step explanation:
To find the rate at which Mario rides his bike in feet per second, use the given information that he rides past each 300-foot block in 50 seconds. The rate can be calculated using the formula rate = distance / time. Given that each block is 300 feet long and it takes Mario 50 seconds to pass one block, the rate is:
rate = 300 feet / 50 seconds = 6 feet/second.
Therefore, Mario rides his bike at a rate of 6 feet per second, making the correct answer (a) 6 feet per second.