Question

Jina's fish tank has 17 liters of water in it. She plans to add 5 liters per minute until the tank has at least 47 liters. What are the possible numbers of minutes Jina could add water?Use t for the number of minutes.Write your answer as an inequality solved for t.

Answer 1

The initial amount of water in the tank: 17 liters

Jina adds water into the tank at a rate of 5 liters per minute, so the amount of water in the tank after t minutes is:

$V(t)=17+5t$

She plans to add 5 liters per minute until the tank has at least 47 liters. The last statement defines an inequality:

$V(t)\geqslant47$

Using the definition of V(t):

$\begin{gathered} 17+5t\geqslant47 \\ 5t\geqslant30 \\ \\ \Rightarrow t\geqslant6\text{ minutes} \end{gathered}$

Jina must add water for at least 6 minutes.