I honestly think B but I'm not sure
DB/dt = 1/5(100 - B)
5/(100 - B) dB = dt
-5 ln (100 - B) = t + C
Since B(0) = 20, then
-5 ln (100 - 20) = C
i.e. C = -5 ln 80
Thus -5 ln (100 - B) = t - 5 ln 80
or t = 5 ln 80 - 5 ln (100 - B) = 5 ln (80 / (100 - B))
When the weight = 40 grams
t = 5 In (80 / 100 - 40) = 5 In (80 / 60) = 5 ln (4/3) = 1.438 days
Rate of weight gain = 40 / 1.438 = 27.8 grams per day
When the weight = 70 grams
t = 5 ln (80 / 100 - 70) = 5 ln (80 / 30) = 5 ln (8/3) = 4.9 days
Rate of weight gain = 70/4.9 = 14.27 grams per day.
Therefore, the duck gains weight faster when it weighs 40 grams.
Response/ NonResponse: Some students might be too tired to answer the question or in converse, a student might feel that his or her grade might be reflected on the survey since it is not anonymous, he or she might sugarcoat the answer. (incorrect response bias)
