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3 years ago

What is the value of x when x + 7 = 21?

Mathematics

2 answers:

sergij07 [2.7K]3 years ago

6 0

Answer:14

Step-by-step explanation:

x + 7 = 21

group like terms

x = 21 - 7

When positive cross = sign it turns negative

x = 14

Yuki888 [10]3 years ago

4 0

X + 7 = 21

- 7 - 7

x = 14

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Two mechanics worked on a car. The first mechanic charged $65 per hour, and the second mechanic charged $90 per hour. The mechan

Katena32 [7]

Answer:

First mechanic worked 20 hours and second mechanic worked 5 hours

Step-by-step explanation:

Let the number of hours the first mechanic worked = $a$

Let the number of hours the second mechanic worked = $b$

Therefore, we can write 2 equations and then solve them simultaneously:

$a+b=25$

$65a+90b=1750$

Rearranging the first equation: $a=25-b$

and substituting into the second equation to find $b$ :

$65(25-b)+90b=1750$

$1625-65b+90b=1750\\
25b=125\\
b=5$

Now sub $b=5$ into the first equation to find $a$

$a+5=25\\
a=20$

Therefore, first mechanic (a) worked 20 hours and second mechanic (b) worked 5 hours

4 0

2 years ago

Convert 2000 g/l to the unit g/ml

balu736 [363]

$\frac{2 \000 g}{l} = \ ? \ \frac{g}{ml} \\ \\ 1 \ l = 1 \ 000 \ ml \\ \\\frac{2\ 000 \ g}{l} =\frac{2 \000 \ g}{1 \000\ ml} = 2.0 \ \ \frac{g}{ml}$

6 0

3 years ago

Read 2 more answers

It is known that diskettes produced by a cer- tain company will be defective with probability .01, independently of each other.

zheka24 [161]

Answer:

1.27%

Step-by-step explanation:

To solve this problem, we may consider a binomial distribution where a customer can either accept or reject (and return) the diskette package.

Lets consider some aspects:

1. From the formulation of the exercise we know that a package is accepted if it has at most 1 defective diskette. So our event A is defined as:

A = 0 or 1 defective diskette

2. The probability of a diskette being defective is 0.01

3. Each package contains 10 diskettes.

If X is defined as number of defective diskettes in the package, the probability of X is given by a binomial distribution with probability 0.01 and n=10

X ~ Bin(p=0.01, n=10)

Let us remember the calculation of probability for the binomial distribution:

$P(X=x)=nCx*p^{x}*(1-p)^{(n-x)}$ with x = 0, 1, 2, 3,…, n

Where

n: number of independent trials

p: success probability

x: number of successes in n trials

In our case success means finding a defective diskette, therefore

n=10

p=0.01

And for x we just need 0 or 1 defective diskette to reject the package

Hence,

$P(X=x)=10Cx*0.01^{x}*(1-0.01)^{(10-x)}$ with x = 0, 1

So,

$P(A)=P(X=0)+P(X=1)$

$P(A)=10C0*0.01^{0}*(1-0.01)^{(10-0)} + 10C1*0.01^{1}*(1-0.01)^{(9)}$

$P(A)=0.99^{10}+10*0.01*0.99^{9}$

$P(A)=0.9957$

Now, because we have 3 packages and we might reject just 1 of them, we can find this probability like this:

$3*(1-P(A))*P(A)*P(A) = (1-0.9957)*0.9957*0.9957=0.0127$

Finally, we have that the probability of returning exactly one of the three packages is 1.27%

3 0

3 years ago

Perform the following calculations without rewriting the numbers in decimal form.

Bingel [31]

Answer:

After multiplication number will be $3.408\times \times 10^{28}$

Step-by-step explanation:

We have given numbers which has to multiply using scientific notation

That are $1.42\times 10^{15}\times 2.4\times 10^{13}$

We have to multiply the above number using scientific notation

We know that when two number are multiplied then there exponent power is being added

So when we multiply $1.42\times 10^{15}\times 2.4\times 10^{13}$ there power will be added and after multiplication number will be $3.408\times \times 10^{28}$

6 0

3 years ago

Please show work thank you math experts

MakcuM [25]

Answer:

See below

Step-by-step explanation:

1) The distribution is skewed left because the majority of the data lies in the left tail.

2) Given what we answered in #1, the mean is going to be the closest of the three measures of central tendency, with the median behind the mean, and the mode behind the median.

3) An outlier is a piece of data that is furthest away from of a set of observed data.

3 0

2 years ago