State the name of the angle

The average heights of x number of girls and 15 boys is 123. if the average heights of boys is 125 and that of girls is 120.find

mamaluj [8]

Answer:

$x = 10$ . In other words, there number of girls is $10$ .

Step-by-step explanation:

The average of a number of measurements is equal to the sum of these measurements over the number of measurements.

$\displaystyle \text{Average} = \frac{\text{Sum of measurements}}{\text{Number of measurements}}$ .

Rewrite to obtain:

$\begin{aligned}& \text{Sum of measurements}= (\text{Number of measurements}) \times (\text{Average}) \end{aligned}$ .

For this question:

$\begin{aligned}& \text{Sum of heights of boys} \\ &= (\text{Number of boys}) \times (\text{Average height of boys}) \\ &= 15 \times 125 = 1875\end{aligned}$ .

$\begin{aligned}& \text{Sum of heights of girls} \\ &= (\text{Number of girls}) \times (\text{Average height of girls}) \\ &= x \times 120 = 120\, x\end{aligned}$ .

Therefore:

$\begin{aligned}& \text{Sum of boys and girls} \\ &= \text{Sum of heights of boys} + \text{Sum of heights of girls}\\ &= 1875 + 120\, x\end{aligned}$ .

On the other hand, there are $(15 + x)$ boys and girls in total. Using the formula for average:

$\begin{aligned}& \text{Average height of boys and girls} \\ &= \frac{\text{Sum of heights of boys and girls}}{\text{Number of boys and girls}} \\ &= \frac{1875 + 120\, x}{15 + x}\end{aligned}$ .

From the question, this average should be equal to $123$ . In other words:

$\displaystyle \frac{1875 + 120\, x}{15 + x} = 123$ .

Solve this equation for $x$ to obtain:

$1875 + 120\, x= 123\, (15 + x)$ .

$(123 - 120)\, x = 1875 - 123 \times 15$ .

$x = 10$ .

In other words, the number of girls here is $10$ .

5 0

3 years ago

For math Equations what is 4x + 5 = x + 8??

vfiekz [6]

Answer:

x = 1

Step-by-step explanation:

To solve for a variable, you need to get the variable on one side of the equation, and by itself.

4x + 5 = x + 8

4x = x + 3 --- subtract 5 from both sides

3x = 3 --- subtract x from both sides

x = 1 --- divide both sides by 3

3 0

3 years ago

Read 2 more answers

Lovell decorates reclaimed shorts and sells them. She pays $420 per month in rent and $21 in expenses for each pair of shorts. S

kirill [66]

Answer: 30 pairs of shorts

21x+420=35x
subtract 21x from both sides of the equation.
420=14x
get rid of the x by division
420/14
you get 30 =x

8 0

3 years ago

How i can write that numbers in letters/ como los escriboo en letras

Klio2033 [76]

Six hundred ninty three thousand, five thousand six hundred ninty nine

Three hundred fourty thousand two thousand and eighty nine

I’m confused on the comma for the last 2?

7 0

2 years ago

An arithmetic progression is a sequence of numbers in which the distance (or difference) between any two successive numbers if t

notsponge [240]

Answer:[m, m+d, m+2d, - - - - -, n]

Step-by-step explanation:

We know the formula for arithmetic progression is a_(n) = a_(1) + (n-1)d

Where a_(n) is the nth term of the sequence

a_(1) is the first term of the sequence

n is the number of the term like if we are talking about 7th term so the n is 7.

d is the difference between two successive terms.

For this problem we know our first term that is m, our last term that is n and our difference that is d.

For second term we will use the formula

a_(2) = m + (2-1)d

a_(2) = m + (1)d

a_(2) = m + d

Similarly,

a_(3) = m + (3-1)d

a_(3) = m + (2)d

a_(3) = m + 2d

3 0

3 years ago