In a group of students, 12 read Mathematics, 15 read Statistics, 11 read Physics, 4 read Mathematics only, 7 read statistics only, 3 read Statistics and Physics only and 1 read Mathematics and Statistics only. Type in the number of students who were there altogether. (The universal set)

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!

10 miles

step-by-step explanation:

i got 86 for this

hope this !

if you need an explanation just ask

it can be to see completed examples before writing, in order to examine what makes for an effective piece. see how these intros give some context before posing the topic and lead naturally into the body paragraphs, where the evidence will be listed. you can imagine how the author has organized the rest of the piece.

"we buried my cousin last summer. he was 32 when he hanged himself from a closet coat rack in the throes of alcoholism, the fourth of my blood relatives to die prematurely from this deadly disease. if america issued drinking licenses, those four men—including my father, who died at 54 of liver failure—might be alive today. that is a good example piece   some steps that are .

. writing something that happened to you

.read a book you like to get ideas from there

. lastly you can make a venn diagram

hope this plz make brainliest

step-by-step explanation: