Answer
$x\lt7.18$
Work Step by Step
Let $x$ be the time of the last trial.
The conditions of the problem translate to
\begin{array}{l}\require{cancel}
\dfrac{6.85+7.04+6.93+x}{4}\lt7.0
.\end{array}
Using the properties of inequality, then
\begin{array}{l}\require{cancel}
4\cdot\dfrac{6.85+7.04+6.93+x}{4}\lt4\cdot7.0
\\\\
6.85+7.04+6.93+x\lt28
\\\\
20.82+x\lt28
\\\\
x\lt28-20.82
\\\\
x\lt7.18
.\end{array}
