Final answer:
To calculate the probability that a randomly selected bike from the store weighs over 20 kg, we need to calculate the z-score of 20 kg using the formula z = (x - µ) / σ.
Step-by-step explanation:
To calculate the probability that a randomly selected bike from the store weighs over 20 kg, we need to calculate the z-score of 20 kg using the formula z = (x - μ) / σ, where x is the value we want to find the probability for, μ is the average weight, and σ is the standard deviation.