First combine the like terms in 4F + (-21)+10 F

Grade 7th math anybody know the answer

TiliK225 [7]

Our answer is attached.

I hope it helped.

=)

4 0

3 years ago

Carla and Frank can each wash a car and clean the interior in 2 hours, but Missy needs 3 hours to do the work. If the three work

irina1246 [14]

Remark

Start by figuring this out for 1 car. Worry about the 7 part when you find 1.

This problem is used quite frequently in physics. For example resistors in parallel use the same equation.

Formula

1/frank + 1/carla + 1/missy = 1/ time taken to do 1 mar.

Givens

Frank = 2 hours

Carla = 2 hours

Missy = 3 hours.

Substitute and Solve

1/2 + 1/2 + 1/3 = 1/Three_together.

3/6 + 3/6 + 2/6 = 1/Three_together.

8/6 = 1/Three_together. Cross multiply

8 * Three_Together = 6*1

8 * Three_Together = 6 Divide by 8

Three_Together = 6/8 = 3/4 = 0.75 hours. or 45 minutes for 1 car

Seven Cars

For 7 cars multiply 0.75 by 7

7 * 0.75 = 5.25 hours. <<<< Answer

7 0

3 years ago

A group of high school athletes has an average GPA of 2.7 with a standard deviation of 0.9. a)Find the percentage of athletes wh

mart [117]

Answer:

a) The percentage of athletes whose GPA more than 1.665 is 87.49%.

b) John's GPA is 3.645.

Step-by-step explanation:

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

$\mu = 2.7, \sigma = 0.9$

a)Find the percentage of athletes whose GPA more than 1.665.

This is 1 subtracted by the pvalue of Z when X = 1.665. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{1.665 - 2.7}{0.9}$

$Z = -1.15$

$Z = -1.15$ has a pvalue of 0.1251

1 - 0.1251 = 0.8749

The percentage of athletes whose GPA more than 1.665 is 87.49%.

b) John's GPA is more than 85.31 percent of the athletes in the study. Compute his GPA.

His GPA is X when Z has a pvalue of 0.8531. So it is X when Z = 1.05.

$Z = \frac{X - \mu}{\sigma}$

$1.05 = \frac{X - 2.7}{0.9}$

$X - 2.7 = 1.05*0.9$

$X = 3.645$

John's GPA is 3.645.

8 0

3 years ago

Twenty-five blue and twenty-five yellow marbles are placed in a jar. Thirty-four marbles are removed from the jar and put in a s

GrogVix [38]

Answer:

a) Let b represent the number of blue marbles placed in the second jar. Then 34-b is the number of yellow marbles in the second jar, and 25 - (34-b) is the number of yellow marbles remaining in the first jar. That value simplifies to b-9. The positive difference between b and (b-9) is 9.

b) Let n, d, p represent the numbers of nickels, dimes, and pennies, respectively.

.. (5n + 10d + p)/(n + d + p) = 7 ... the average value of the collection is 7 cents per coin

.. (5(n-1) + 10d + (p+5))/((n-1) + d + (p+5)) = 6 ... replacing one nickel with pennies changes the average to 6 cents per coin

Multiplying by the denominator and subtracting the right side of each resulting equation gives

.. 10d + 5n + p = 7d + 7n + 7p

.. 10d + 5n + p = 6d + 6n + 6p + 24

Subtracting the second equation from the first gives

.. 0 = d + n + p - 24 ... tells us the total number of coins is 24. This tells us the total value is $1.68 = 24*$0.07.

This sum will consist of at least 3 pennies. If that is all the pennies, then the remaining 21 nickels and dimes must add to $1.65. If all were nickels, the value of the 21 coins would be $1.05. We have $0.60 more than that. For each nickel traded for a dime, we gain $.05, so 12 of the 21 nickels must be traded for dimes to raise the total coin value to $1.65.

Alternatively, you can write two equations in the two unknowns:

.. d + n = 21

.. 10d + 5n = 165

Subtracting 5 times the first equation from the second gives

.. 5d = 60 ... which gives the same answer as reasoned above.

There are 3 pennies, 9 nickels, 12 dimes. (If there are 8 pennies to start, then the number of nickels is zero, so it is impossible to trade one for 5 pennies. The solution shown is the only one.)

7 0

3 years ago

<img src="https://tex.z-dn.net/?f=27%3D%281%2F3%29x%2F2%5C%5C" id="TexFormula1" title="27=(1/3)x/2\\" alt="27=(1/3)x/2\\" align=

ICE Princess25 [194]

Answer:

x = 162

Step-by-step explanation:

The equation editor lets you properly write exponents, so we have to assume that your equation is supposed to be equivalent to ...

27 = x/6

27·6 = x = 162 . . . . multiply by 6

_____

On the off chance you intend ...

$27=\left(\dfrac{1}{3}\right)^{\dfrac{x}{2}}$

you can solve this by taking logarithms and dividing by the coefficient of x. Using base 3 for the logarithm may be easiest.

$\log_3{(27)}=\dfrac{x}{2}\log_3{(3^{-1})}\\\\3=-\dfrac{x}{2} \qquad\text{simplify}\\\\-6=x \qquad\text{multiply by -2}$

This version of the equation has solution x = -6.

4 0

3 years ago