The least possible number among the missing scores is 83.
Explanation:
If we arrange the test scores in non decreasing order then obviously
will be at the third position since it is the median.
As it is not bimodal and the given mode is greater than the median the arrangement of test scores should be as given below.(assuming the unknown scores be
and
)

Now let us verify it with the mean;

⇒

⇒

Now for
to be least;
must be maximum possible value here.
Therefore
is equal to

⇒
