Is the sum of two rational numbers always rational

Mathematics

1 answer:

Pepsi [2]2 years ago

8 0

Answer:

in short, Yes they are always rational.

here's why...

E.g. suppose $\frac{c}{d}$ and $\frac{a}{b}$ are fractions, that means that a,b,c,d are all integers, and b and d are not zero. finding the sum the numerator, and denominator would also have to be integers. the denominator of the sum can't be zero since the denominators of the fractions were not zero, and would give $\frac{ad+bc}{bd}$ and since they are bound by addition (sum means addition) they must also be rational since eit would equal a bigger integer than initially had

Step-by-step explanation:

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At a Psychology final exam, the scores are normally distributed with a mean 73 points and a standard deviation of 10.6 points. T

USPshnik [31]

Answer:

The score that separates the lower 5% of the class from the rest of the class is 55.6.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

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

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.

In this question:

$\mu = 73, \sigma = 10.6$