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3 years ago

Two-thirds of a class are boys. If there are 12 boys, then how many girls are in the class?

Mathematics

1 answer:

son4ous [18]3 years ago

6 0

Step-by-step explanation:

so 2/3 OF the class are boys...

***REMEMBER IN MATHEMATICS, ^OF^ IS USED TO SAY MULTPLICATION***

so 2/3 OF class(x) are boys and there are 12 boys...

so 2/3 * x = 12

12 / (2/3) = x

to solve use the Keep, Change, Flip method

Keep 12, change / to multiplication, flip 2/3 to 3/2

it becomes 12 * 3/2 and to solve easier 12 is same thing as 12/1

12/1 * 3/2

Multiply across (numerator by numerator and denominator by denominator)

(12*3) / (1*2) = 36 / 2

Simplify

So the class has 18 students, and 2/3 of boys (12 of the students)

we can solve for how many girls are in the class

Depending on how your teacher wants to see the work:

either 18 - 12 = 6

or 1/3 * 18 which we rewrite as 1/3 * 18/1 = (1*18)/(3*1) which is 18/3... simplified it is 6

There are 6 girls in the class.

Hope this helps! :)

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3 years ago

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Answer:

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3 years ago

I need help. Give an explanation, please!

AURORKA [14]

Answer:

y=35+x+15x/100. since x is the money earn so 15percent of x

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3 years ago

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Recall that m(t) = (1/2)^t/h for radioactive decay, where h is the half-life. Suppose that a 500g sample of phosphorus-32 decays

katrin2010 [14]

The question is incomplete, here is the complete question:

Recall that m(t) = m.(1/2)^t/h for radioactive decay, where h is the half-life. Suppose that a 500 g sample of phosphorus-32 decays to 356 g over 7 days. Calculate the half life of the sample.

<u>Answer:</u> The half life of the sample of phosphorus-32 is $14.28days^{-1}$

<u>Step-by-step explanation:</u>

The equation used to calculate the half life of the sample is given as:

$m(t)=m_o(1/2)^{t/h}$

where,

m(t) = amount of sample after time 't' = 356 g

$m_o$ = initial amount of the sample = 500 g

t = time period = 7 days

h = half life of the sample = ?

Putting values in above equation, we get:

$356=500\times (\frac{1}{2})^{7/h}\\\\h=14.28days^{-1}$

Hence, the half life of the sample of phosphorus-32 is $14.28days^{-1}$

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4 years ago

If y=8 when x =3, find y when x=45

Art [367]

Let's make things easier by simplifying things.

y = 8 and x = 3 is more likely to be understood as a ratio. So for the rest of the answer, their relationship would be represented as y:x

Thus: y:x = 8:3

The problem would be finding y when x = 45

Let us proceed on using the previous equation and substitute x with 45 which would look like this:

y:45 = 8:3

Ratios can also be expressed as fractions which would make things more understandable and easy to solve. So the new form of our equation would be like this:

y/45 = 8/3

Then we proceed with a cross multiplication where the equation becomes like as what is shown below:

3y = 45 * 8

From there, you can solve it by multiplying 45 and 8 then dividing the product with 3 to get y

3y = 360

y = 120

Another way of looking at the problem, especially problems like these, is to take the whole question or statement as an equation. it would probably look like this:

y = 8 when x = 3 : y = ? when x = 45

This would make you understand what approach you can use to solve the given problem.

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3 years ago

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