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3 years ago

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Mathematics

2 answers:

ale4655 [162]3 years ago

6 0

Answer:

4*x+4*7

4(x+7)

15y+11

Step-by-step explanation:

Respective order:

PEMDAS

DISTRIBUTIVE PROPERTY

Simplify common terms

Yuri [45]3 years ago

3 0

Answer:

What is the help you need

Plz repost clearly

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At a bake sale, as student spent $11.00 buying 3 brownies and 5 cookies. His friend spent $3.95 buying 1 brownie and 2 cookies.

dybincka [34]

Answer:

$2.25

Step-by-step explanation:

Let "b" be the price of 1 brownie and "c" the price of 1 cookie.

At a bake sale, a student spent $11.00 buying 3 brownies and 5 cookies. Symbolicaly,

3 b + 5 c = 11.00 [1]

His friend spent $3.95 buying 1 brownie and 2 cookies. Symbolicaly,

1 b + 2 c = 3.95

b = 3.95 - 2c [2]

If we replace [2] in [1], we get

3 (3.95 - 2c) + 5 c = 11.00

11.85 - 6c + 5c = 11.00

c = 0.85

If we replace c = 0.85 in [2], we get

b = 3.95 - 2 (0.85) = 2.25

8 0

3 years ago

What is the value of x? x+15=2x-40

IrinaVladis [17]

Answer:

55 =x

Step-by-step explanation:

x+15=2x-40

Subtract x from each side

x-x+15=2x-x-40

15 = x-40

Add 40 to each side

15+40 = x-40+40

55 =x

7 0

2 years ago

Read 2 more answers

A cement walkway of uniform width has been built around an in-ground rectangular pool. the area of the walkway is 1344 square fe

Elza [17]

Answer:

6 feet.

Step-by-step explanation:

Dimensions of the Pool =80 feet long by 20 feet wide

Area of the walkway =1344 square feet.

If the width of the walkway=w

Length of the Larger Rectangle =80+2w
Width of the Larger Rectangle =20+2w

Area of the Walkway =Area of the Larger Rectangle - Area of the Pool

$1344=(80+2w)(20+2w)-(80*20)\\1344=80*20+160w+40w+4w^2-80*20\\4w^2+200w=1344\\4w^2+200w-1344=0\\We factorize\\4(w^2+50w-336)=0\\4(w^2-6w+56w-336)=0\\w(w-6)+56(w-6)=0\\(w-6)(w+56)=0\\w-6=0$ or $ w+56=0\\w=6$ ft or $ w=-56$ \\Therefore, the width of the walkway , w=6 feet.$

6 0

2 years ago

Calls to a customer service center last on average 2.8 minutes with a standard deviation of 1.4 minutes. An operator in the call

Natali5045456 [20]

Answer:

The expected total amount of time the operator will spend on the calls each day is of 210 minutes.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

n-values of normal variable:

Suppose we have n values from a normally distributed variable. The mean of the sum of all the instances is $M = n\mu$ and the standard deviation is $s = \sigma\sqrt{n}$