Answer:
1 and 3
15 and 13
15 and 7
1 and 9
Step-by-step explanation:
Here we have to find the probability
. Now express the probability in terms of standard normal cumulative distribution function. That is
.

Now you can look up the probability from the standard normal tables. Its value is

Answer:
Z scores between -0.995 and 0.995 bound the middle 68% of the area under the stanrard normal curve
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the z-score 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 p-value, we get the probability that the value of the measure is greater than X.
Middle 68%
Between the 50 - (68/2) = 16th percentile and the 50 + (68/2) = 84th percentile.
16th percentile:
X when Z has a pvalue of 0.16. So X when Z = -0.995
84th percentile:
X when Z has a pvalue of 0.84. So X when Z = 0.995.
Z scores between -0.995 and 0.995 bound the middle 68% of the area under the stanrard normal curve
We can use vertical opposite angles. Which means the opposite angles where 2 lines intersects is the same.
3x + 50 = 6x - 10 (vert. Opp. Angles)
3x = 6x - 60
-3x = - 60
X = 20°