Select the best answer. the web portal aol places opinion poll questions next to many of its news stories. simply click your response to join the sample. one of the questions in january 2008 was "do you plan to diet this year? " more than 30,000 people responded, with 68% saying "yes." you can conclude that
(a) about 68% of americans planned to diet in 2008.
(b) the poll used a convenience sample, so the results tell us little about the population of all adults.
(c) the poll uses voluntary response, so the results tell us little about the population of all adults.
(d) the sample is too small to draw any conclusion.
(e) none of these.

The correct answer is (c) the poll uses voluntary response, so the results tell us little about the population of all adults.

Step-by-step explanation:

You can't conclude (a) because this question hasn't be made to all the Americans.  

You can't conclude (b) because the poll doesn't use any convenience for the selection of the sample

You can't conclude (d) because this is not a poll with a premeditated sample, therefore, the size is inconclusive.  

You can conclude (c) because the poll was available for anyone who voluntary wanted to answer it.

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

equation image indicator

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!

50=33x+22

step-by-step explanation: