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3 years ago

What is the value of x? Please help

Mathematics

1 answer:

expeople1 [14]3 years ago

7 0

Answer: x = 21

Step-by-step explanation:

5x + (3x + 12) = 180

8x + 12 = 180

8x = 168

168/8 = 21

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You have been saving nickels, dimes, and quarters in a jar for about a year. You decide to see how much money you've saved up. W

anyanavicka [17]

Answer:

x = number of nickels = 127

y = number of dimes = 156

z = number of quarters = 78

Step-by-step explanation:

Let

x = number of nickels

y = number of dimes

z = number of quarters

Total worth of the coins = $41.45

Total number of coins = 361

x + y + z = 361 (1)

dime = $0.1,

nickel = $0.05

quarter = $0.25

0.05x + 0.1y + 0.25z = 41.45 (2)

twice as many dimes as quarters.

y = 2z

Substitute y = 2z into (1) and (2)

x + 2z + z = 361

0.05x + 0.1(2z) + 0.25z = 41.45

x + 3z = 361

0.05x + 0.2z + 0.25z = 41.45

x + 3z = 361 (3)

0.05x + 0.45z = 41.45 (4)

Multiply (4) by 20

x + 3z = 361 (3)

x + 9z = 829 (5)

Subtract (3) from (5)

9z - 3z = 829 - 361

6z = 468

Divide both sides by 6

z = 468 / 6

= 78

z= 78

Recall,

y = 2z

= 2(78)

= 156

y = 156

Substitute the value of y and z into

x + y + z = 361

x + 156 + 78 = 361

x + 234 = 361

x = 361 - 234

= 127

x= 127

x = number of nickels = 127

y = number of dimes = 156

z = number of quarters = 78

6 0

3 years ago

Find the slope of a line that is vertical and passes through the point (-1,2)

Greeley [361]

Answer:

slope: undefined

Step-by-step explanation:

vertical line slope = (y-y') / (x-x')

x-x' = 0

slope: undefined

3 0

2 years ago

Plot the graph y=3x from x=-1 from x=2

Ira Lisetskai [31]

Answer:

(-1,-3) and (2,6)

Step-by-step explanation:

Plug x (x value) into equation (outputs y value)

(x value, y value) which gives coordinates

6 0

2 years ago

a test consists of 10 true false questions to pass a test a student must answer at least six questions correctly if a student gu

Delicious77 [7]

Answer:

$P(X \geq 6) = P(X=6) +P(X=7) +P(X=8) +P(X=9) +P(X=10)$

And using the probability mass function we got:

$P(X=6)=(10C6)(0.5)^6 (1-0.5)^{10-6}=0.205$

$P(X=7)=(10C7)(0.5)^7 (1-0.5)^{10-7}=0.117$

$P(X=8)=(10C8)(0.5)^8 (1-0.5)^{10-8}=0.0439$

$P(X=9)=(10C9)(0.5)^9 (1-0.5)^{10-9}=0.0098$

$P(X=10)=(10C10)(0.5)^{10} (1-0.5)^{10-10}=0.000977$

And adding the values we got:

$P(X\geq 6) = 0.377$

The best answer would be:

D. 0.377

Step-by-step explanation:

Let X the random variable of interest, on this case we now that:

$X \sim Binom(n=10, p=0.5)$

The probability mass function for the Binomial distribution is given as:

$P(X)=(nCx)(p)^x (1-p)^{n-x}$

Where (nCx) means combinatory and it's given by this formula:

$nCx=\frac{n!}{(n-x)! x!}$

For this case in order to pass he needs to answer at leat 6 questions and we can rewrite this:

$P(X \geq 6) = P(X=6) +P(X=7) +P(X=8) +P(X=9) +P(X=10)$

And using the probability mass function we got:

$P(X=6)=(10C6)(0.5)^6 (1-0.5)^{10-6}=0.205$

$P(X=7)=(10C7)(0.5)^7 (1-0.5)^{10-7}=0.117$

$P(X=8)=(10C8)(0.5)^8 (1-0.5)^{10-8}=0.0439$

$P(X=9)=(10C9)(0.5)^9 (1-0.5)^{10-9}=0.0098$

$P(X=10)=(10C10)(0.5)^{10} (1-0.5)^{10-10}=0.000977$

And adding the values we got:

$P(X\geq 6) = 0.377$

The best answer would be:

D. 0.377

8 0

3 years ago

The z-score with a two-tail probability of 0.55 is

katrin2010 [14]

Answer:

-0.61

Step-by-step explanation:

0.55/2=0.275

Read 0.275 from normal distribution tables

Gives -0.61

7 0

2 years ago