Final answer:
The total amount of light energy the plants received over 7 days is 35 kcal.
Step-by-step explanation:
The total amount of light energy the plants received over 7 days can be calculated using the equation W = L x t, where W is the total amount of light energy, L is the average daily light energy, and t is the time in days. Given that the plants received an average of 5 kilocalories of light energy per day, we can substitute L = 5 and t = 7 into the equation to find W:
W = 5 x 7 = 35 kcal
Therefore, the total amount of light energy the plants received over 7 days is 35 kcal.