Mark and Mike are brothers. The sum of their ages is eleven. Mike's age is ten

Mathematics

2 answers:

ivann1987 [24]3 years ago

8 0

Answer:mark is 7. Mike is 4

Step-by-step explanation:x+y=11. Y=2x-10 thus substituting for y in equation1 we have x+2x-10=11. 3x-10=11. 3x=11+10. 3x=21. X=21/3. X=7. Mike =(2×7)-10=14-10=4

o-na [289]3 years ago

3 0

Step-by-step explanation:

Mark's age is x

so Mike's age is

$2x - 10$

and we know that the sum of their ages is eleven so:

2x+x- 10 = 11

3x-10=11/+10

3x=21/÷3

x=7

Mark is 7 years old and

Mike is 4 years old.

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A set of test scores is normally distributed with a mean of 130 and a standard deviation of 30 What score is necessary to reach

nlexa [21]

Answer:

A score of 150.25 is necessary to reach the 75th percentile.

Step-by-step explanation:

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$Z = \frac{X - \mu}{\sigma}$

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.

A set of test scores is normally distributed with a mean of 130 and a standard deviation of 30.

This means that $\mu = 130, \sigma = 30$