Given:
D varies as R and S, and inversely as t.
D=12, R=3, S=20, and t=5
To find:
The value of D when R=15, S=4 and t=8.
Solution:
It is given that D varies as R and S, and inversely as t. So,
...(i)
Where, k is the constant of proportionality.
We have, D=12, R=3, S=20, and t=5. Substituting these values in (i), we get
Substituting in (i), we get the required equation.
We need to find D when R=15, S=4 and t=8. Substituting R=15, S=4 and t=8 in the above equation, we get
Therefore, the required value of D is 7.5.