Respuesta :

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D[tex] \alpha [/tex]t
D=kt
108=k(4)
108=4k
k=[tex] \frac{108}{4} [/tex]
k=27
The equation connecting D and t is;
D=27t
When t=7,
D=27*7
D= 189

Answer:

189

Step-by-step explanation:

Given : D varies directly with t and D is 108 when t is 4

To Find:  Find D when t is 7

Solution:

D varies directly with t

D ∝ t

So, [tex]D=kt[/tex]

where k is the constant of proportionality

Now we are given that D is 108 when t is 4

So, [tex]108=k(4)[/tex]

[tex]\frac{108}{4}=k[/tex]

[tex]27=k[/tex]

Thus the constant of proportionality i.e. k = 27

So, [tex]D=27t[/tex]

Now substitute t = 7

So,  [tex]D=27(7)[/tex]

[tex]D=189[/tex]

So, D = 189 when t = 7

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