The answer to 8a. is 17, the answer to 8b. is 3.9, the answer to 8c. is 1 / 2, the answer to 8d. is 7 7 / 8, the answer to 9a. is commutative property, the answer to 9b. is multiplicative identity property, the answer to 9c. is associative property, and the answer to 9d. is additive inverse property.
Regarding the whole "explain using mental math" thing, I pretty much just used the fact that 8a. and 8b. both had the same number of decimal places. For 8c., I just made each number have a denominator of 10. And last, for 8d., all of the denominators were already the same, which made it pretty easy. I apologize for this section of my answer being so informal lol, I haven't had to do these kinds of problems in like 5 years <span />
6 goes into 64 ten times with a remainder of 4
you know that
Answer:
The percentage of students who scored below 620 is 93.32%.
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean 
and standard deviation 
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this question, we have that:
Percentage of students who scored below 620:
This is the pvalue of Z when X = 620. So
has a pvalue of 0.9332
The percentage of students who scored below 620 is 93.32%.
The absolute difference between the greatest and the least of these three numbers in the arithmetic sequence is 10.
The sequence is an arithmetic sequence. Therefore,
d = common difference
let
a = centre term
Therefore, the 3 consecutive term will be as follows
a - d, a, a + d
a - d + a + a + d = 27
3a = 27
a = 27 / 3
a = 9
Therefore,
(a-d)² + (a)² + (a + d)² = 293
(a²-2ad+d²) + 9² + (a² + 2ad + d²) = 293
(81 - 18d + d²) + 81 + (81 + 18d + d²) = 293
243 + 2d² = 293
2d² = 50
d² = 50 / 2
d = √25
d = 5
common difference = 5
Therefore, the 3 numbers are as follows
9 - 5 , 9, 9 + 5 = 4, 9, 14
The difference between the greatest and the least of these 3 numbers are as follows:
14 - 4 = 10
learn more on Arithmetic progression: brainly.com/question/25749583?referrer=searchResults
