Step-by-step explanation:
x = number of hours A
y = number of hours B
x + y = 23
5.7x + 7.1y = 143.7
from the first equation we get
x = 23 - y
this we use in the second
5.7×(23 - y) + 7.1y = 143.7
131.1 - 5.7y + 7.1y = 143.7
1.4y = 12.6
y = 12.6/1.4 = 9
x = 23 - y = 23 - 9 = 14
she worked 14 hours on job A and 9 hours on job B.
Answer:
Step-by-step explanation:
-95/6 or negative ninety-five over six
Answer:
14.63% probability that a student scores between 82 and 90
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 problem, we have that:

What is the probability that a student scores between 82 and 90?
This is the pvalue of Z when X = 90 subtracted by the pvalue of Z when X = 82. So
X = 90



has a pvalue of 0.9649
X = 82



has a pvalue of 0.8186
0.9649 - 0.8186 = 0.1463
14.63% probability that a student scores between 82 and 90