Question

If D varies directly with t and D is 105 when t is 3 find D when t is 8

Answer 1

If D varies directly with t and D is 105 when t is 3 then value of D when t is 8 is equal to 280

Solution:

In this sum we have been given that there is a direct relationship between d and t.

If d is 105 when t is 3 so now, we need to find d when t is 8.

To do this we can simply use the unitary method. The definition of unitary method is, the unitary method is a technique for solving a problem by first finding the value of a single unit, and then finding the necessary value by multiplying the single unit value.

Now, according to the definition we need to find the value of d when t is 1.

This can be done as follows:

$D=\frac{105}{3}=35$

Therefore, the value of d when t = 1 is 35.

Now, if the value of t=8 then d becomes:

$D=35 \times 8=280$

Hence, when t=8 the value of d is 280.