The income distribution in a county is a normal distribution with a mean income of $10,000. the top 2.5% of the wage earners earn $18,000 or more. which sentence most closely summarizes this information? 68% of the wage earners earn less than $14,000 each. 16% of the wage earners earn less than $14,000 each. 55% of the wage earners earn less than $14,000 each. 84% of the wage earners earn less than $14,000 each. 95% of the wage earners earn less than $14,000 each.

84% of the wage earners earn less than $14,000 each.

Step-by-step explanation:

The Empirical Rule (68-95-99.7%)-

According to this around 95% of the data will fall within two standard deviations of the mean.

As the bell curve is symmetrical, so the remaining 5% will be divided into 2 equal parts. So 2.5% will be above 2 standard deviation and 2.5% will be below 2 standard deviation.

As it is given that, the top 2.5% of the wage earners earn $18,000 or more, so 18,000 is 2 standard deviation away from the mean 10,000.

i.e

We know that,

where,

X = raw score = 14,000

μ = 10,000

σ = 4,000

Putting the values,

Now, calculating the value from the z score table,

As the probability at is the area below that, so 84% of the wage earners earn less than $14,000 each.

step-by-step explanation:

30% of $420 is 0.30($420) = $126 and $420 + $126 = $546.

or, 130% of $420 is 1.3($420) = $546.

notice that this is not the $600 original list price with which we started.

why doesn't this work?

the method does not work because 30% of $420 is not the same amount as the 30% of $600. it may seem obvious when stated this way, but it is a very common error made on problems of this type. we cannot just use the same percent and get back to the original amount because we are taking that percent of a different value.

to work problems of this type correctly, it is generally best to write an equation for the situation and then solve.

example: since (100% – 30%)(original price) = (sale price)

70% of the   (original price) is $420.

0.7x   = 420

equation image indicator

x = 600

the original cost was $600.

we may also solve this problem using the two-step method. working the problem in two steps requires us to use more algebra skills. we have to know that x = 1x (identity property of multiplicationtext annotation indicator) and that 1x – 0.3x = 0.7x (subtracting like terms). then we solve the problem as follows:

(original price) – 30%(original price) = sale price

x – 0.3x = 420

0.7x = $420

equation image indicator

x = 600

the original cost was $600.  

note that with both of the above methods we do obtain the correct original amount.

example: after a 5% pay raise, hermione is earning $22,680 per year. what was she earning before the pay raise?

105% of (original salary) = current salary

1.05x = 22,680

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x = 21,600

hermione earned $21,600 per year before the pay raise.

this is an example so maybe you will get how to at least do it!

step-by-step explanation:

1