Question 490646
In words:
Average = (total value of items) / (number of items)
Let {{{a}}} = sum of his 3 test scores
Let {{{b}}} = score he needs on next test
given:
(1) {{{  83 = a/3 }}}
(1) {{{ a = 249 }}}
(2) {{{ 86 = ( a + b) / 4 }}}
(2) {{{ 344 = a + b }}}
Substitute (1) into (2)
(2) {{{ 344 = 249 + b }}}
(2) {{{ b = 95 }}}
He needs a 95 on the next test