for a certain exam , a score of 86 was 5 standard deviations above mean and a score of 67 was 2.5 standard deviations above mean . what was the mean score for the exam ?
"mean + 5 sd = 86 mean + 2.5 sd = 67 by solving above equations we get , sd ( absolute value ) = 7.6 mean = 48 ans . c"
divide(add(multiply(86, 2.5), multiply(67, 5)), add(5, const_3.0))