Question 844064
You can't answer the question until you
know how many tests you took before
the last test
Suppose you took 9 tests to give you the 87 average
Your total score up to that point is {{{ 9*87 = 783 }}}
The 10th test adds {{{ 100 }}} to that
{{{ 783 + 100 = 883 }}}
Average = {{{ 883 / 10 }}}
{{{ 883 / 10 = 88.3 }}} average