Answer:
6.08 L/d
Step-by-step explanation:
The data is provided in units of cups (c) and weeks (w). If we divided 630 cups by 3.5 weeks, we would have a rate:
(630 cups)/(3.5 weeks) = 180 cups/week (c/w)
We are asked for a rate in liters per day, or L/d. Lets find a conversion factor to make that change.
We want to go from (c/w) to (L/d).
We know that:
1) There are 4.23 cups in a liter, or 4.23 c/L
2 There are 7 days in a week, or 7 d/w
We want to convert 180 (c/w) to L/d
180 (c/w)
Starting with just the unit:
(c/w)
The second conversion from above tells us that 7 d/w. The beauty of conversion factors is that they can be inverted. 7 d/w is the same as 1w/7d Lets write that as (1/7)w/d.
Now multiply times the original rate:
180 (c/w)*((1/7)(w/d)
The unit w (weeks) cancels, leaving cups, c and d (days): 25.71 c/d
Now use the second conversion factor to change cups, c, to Liters, L.
4.23 c/L [From above]
This can be done as a division with the original unit:
(25.71 c/d)/(4.23 c/L) = 6.08 L/d
c, cups, cancel and L. liters. moves to the top.
For those of us who prefer multiplication over division, it is easy to invert the conversion factor and then multiply, instead of divide:
The inverted factor is
(25.71 c/d)*(0.235 L/c) = 6.08 L/d
Cups, c, cancel, leaving L/d, the desired unit.