Answer:
unreadable score = 35
Step-by-step explanation:
We are trying to find the score of one exam that is no longer readable, let's give that score the name "x". we can also give the addition of the rest of 9 readable s scores the letter "R".
There are two things we know, and for which we are going to create equations containing the unknowns "x", and "R":
1) The mean score of ALL exams (including the unreadable one) is 80
so the equation to represent this statement is:
mean of ALL exams = 80
By writing the mean of ALL scores (as the total of all scores added including "x") we can re-write the equation as:
since the mean is the addition of all values divided the total number of exams.
in a similar way we can write what the mean of just the readable exams is:
(notice that this time we don't include the grade x in the addition, and we divide by 9 instead of 10 because only 9 exams are being considered for this mean.
Based on the equation above, we can find what "R" is by multiplying both sides by 9:
Therefore we can now use this value of R in the very first equation we created, and solve for "x":
<span>The number of ways to permute three correct answers among five questions is 5Choose3 which is 5!/(3!*2!) which equals 10.
We must then have the correct answer three times which happens .25 of the time, and two wrong answers 75 of the time.
So the probability is 10*0.25^3*.75^2 which is 0.087890625 or roughly an 8.8% chance.</span>
The smaller the value of the least increment, the more precise a number is.
Length measured to the nearest 1/8 inch will be more precisely specified than length measured to the nearest 1/4 inch.
_____
In general, precision has little to do with accuracy—how close the measured value is to the actual value. A measurement can be very precise, but just plain wrong. (Many electronic instruments have resolution (precision) that exceeds their accuracy. That is, one or two (or more) of the least-significant displayed digits may be in error.)
Answer:
the final price is $87.84
