Question

The depth of a lake, dd, varies directly with rr, the amount of rainfall last month. if kk is the constant of variation, which equation represents the situation?

Answer 1

Given that the depth varies directly with amount of rainfall, then we shall have:
let d be the depth and r be the rainfall amount
dαr
thus
d=kr
where, k is the constant of proportionality, thus the formula will be:
d=kr