In an exam a score of 58 was 2 standard deviation below the mean and a score of 98 was 3 standard deviation above the mean.
What was the mean score of the exam. The answer is 74.
Can anyone solve this for me??
2007-02-03 19:28:32 · 5 answers · asked by rajagopal r 1 in Science & Mathematics ➔ Mathematics
the difference between 98 and 58 is 40. The total deviations are 5 that is 3 more than and 2 less than mean.
so 1 std deviation = 40/5 = 8
to find mean 58 + 2 std deviations = 58 + 16 = 74
u can also check it back with 98- 3 std devns
2007-02-03 20:24:00 · answer #1 · answered by Anonymous · 1⤊ 0⤋
The standard deviation is 8.
A standard devation is simply a measure of the spread of values. A standard deviation takes on a value and can be determined by a certain formula. It is measuring how widely spread the values in a data set are. Ok think, if the mean of the exams was a 74 and the standard deviation is 8, then the score of 58 is two standard deviations below the mean so... 2x8=16.
and 58+16 =74. So now we know the standard deviation is 8, so the grade of 98 is 3 standard deviations above the mean therefore 8x3= 24. 98-24=74. This one can be easy if you dont have to use the formula. You can just try to plug in numbers and do some simple math.
Im so sorry, I hope I didnt confuse you!
2007-02-03 19:40:26 · answer #2 · answered by Ashley V 2 · 0⤊ 0⤋
time-honored deviation is the conventional distance of each little bit of documents from the recommend. to your occasion, if the conventional (recommend) score on the attempt is sixty six% with a S.D. of sixteen, this suggests that sixty seven% of the individuals of your type had rankings interior the sixty six+/-sixteen factors variety. The sixty seven% is by definition. So approximately 2/3 of your type scored between 50 and eighty two on the examination. 2 time-honored deviations characterize approximately ninety 5% of your type and a pair of time-honored deviations is 32 factors. So ninety 5% of the class scored between 34 and ninety 8 on the examination. 3 time-honored deviations represents ninety 9.7% of the class so maximum anybody scored between 18 and 114 on the examination. desire that facilitates.
2016-09-28 09:52:33 · answer #3 · answered by benisek 4 · 0⤊ 0⤋
out of syllabus!!!
2007-02-04 05:13:48 · answer #4 · answered by Anonymous · 0⤊ 0⤋
this chapter is irritating
2007-02-03 19:34:19 · answer #5 · answered by n nitant 3 · 0⤊ 1⤋