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3 years ago

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A computer has $245 and his commuter savings account. This account changes by -$15 each week he buys a ticket. In one time perio

d The account changes by -$240. For how many weeks did the computer buy tickets?

1 answer:

dezoksy [38]3 years ago

7 0

Answer:

16 weeks

Step-by-step explanation:

Change per week = - $15

Total change = - $240

<u>Number of weeks:</u>

-240/ -15 = 16

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The number of "destination weddings" has skyrocketed in recent years. For example, many couples are opting to have their wedding

crimeas [40]

Answer:

Step-by-step explanation:

Mean = (29.7 + 29.4 + 31.7 + 29.0 + 29.1 + 30.5 + 29.1 + 29.8)/8 = 29.7875

Mean = 29.7875 × 1000 = $29787.5

Standard deviation = √(summation(x - mean)²/n

n = 8

Summation(x - mean)² = (29.7 - 29.7875)^2 + (29.4 - 29.7875)^2 + (31.7 - 29.7875)^2 + (29.0 - 29.7875)^2 + (29.1 - 29.7875)^2 + (30.5 - 29.7875)^2 + (29.1 - 29.7875)^2 + (29.8 - 29.7875)^2 = 5.88875

Standard deviation = √(5.88875/8

s = 0.88

s = 0.88 × 1000 = $880

a) We would set up the hypothesis test. This is a test of a single population mean since we are dealing with mean

For the null hypothesis,

H0:µ ≤ 30000

For the alternative hypothesis,

H1:µ > 30000

This is a right tailed test.

b) The decision rule is to reject the null hypothesis if the significance level of 0.05 is greater than the probability value. If it is otherwise, we would fail to reject the null hypothesis.

c) Since the number of samples is small and no population standard deviation is given, the distribution is a student's t.

Since n = 8

Degrees of freedom, df = n - 1 = 8 - 1 = 7

t = (x - µ)/(s/√n)

Where

x = sample mean = 29787.5

µ = population mean = 30000

s = samples standard deviation = 880

t = (29787.5 - 30000)/(880/√8) = - 0.68

We would determine the p value using the t test calculator. It becomes

p = 0.26

d) Since alpha, 0.1 < the p value, 0.26, then we would fail to reject the null hypothesis.

6 0

3 years ago

saw5 [17]

The above expression is not in its simplest form, and we need to simplify it, that is what asked in the question.

Given equation,

$(9 {x}^{2} - 3x + 7) + ( - 3 {x}^{2} + 2)$

First of all, let's open the parentheses to combine the like terms for simplifying.

$9 {x}^{2} - 3x + 7 - 3 {x}^{2} + 2$

Arranging the like terms, x² with x², x with x and constant terms near to each other.

$9 {x}^{2} - 3 {x}^{2} - 3x + 7 + 2$

Simplying further,

$(9 - 3) {x}^{2} - 3x + 9$

$6 {x}^{2} - 3x + 9$

So, the correct option is C

<u>━━━━━━━━━━━━━━━━━━━━</u>

8 0

4 years ago

I need help with this word problem it’s urgent please help.

harkovskaia [24]

Starting with some solution of volume <em>v</em> and an alcohol concentration of 100<em>c </em>% , if you add 180 mL of 45% isopropyl to it, you get a mixture with a total volume of 180 mL + <em>v</em>.

Each mL of the starting solution contains <em>c</em> mL of alcohol. For example, if the concentration of the starting solution is 80% (so <em>c</em> = 0.8), then each mL contains 80% = 0.8 of one mL of alcohol.

Similarly, each mL of the added solution with 45% concentration contains 0.45 mL of alcohol.

You want the new solution to have a concentration of 70%, so that the ratio of the amount of alcohol in it to the total volume is 70%, meaning

<em>cv</em> + 0.45 (180 mL) = 0.7 (180 mL + <em>v</em>)

and you want to solve for <em>v</em> :

<em>cv</em> + 81 mL = 126 mL + 0.7<em>v</em>

<em>cv</em> - 0.7<em>v</em> = 126 mL - 81 mL

(<em>c</em> - 0.7) <em>v</em> = 45 mL

<em>v</em> = (45 mL) / (<em>c</em> - 0.7)

Judging by context clues, <em>c</em> lies somewhere between 0.7 and 1. (It can't be less than 0.7 because mixing this solution with any other solution of smaller concentration will never yield a solution of higher concentration.)

If, for example, <em>c</em> = 0.8, so that your starting solution is at 80% concentration, then you would need

<em>v</em> = (45 mL) / (0.8 - 0.7) = 450 mL

to be mixed with 180 mL of 45% solution to end up with 180 mL + 450 mL = 630 mL of 70% solution.

As another example, if you're mixing pure alcohol, so that <em>c</em> = 1, you would need

<em>v</em> = (45 mL) / (1 - 0.7) = 150 mL

to make a 180 mL + 150 mL = 330 mL batch of 70% solution. The fact that you would need less of a higher concentration solution is not surprising.

3 0

3 years ago

2. A machine burns m gallons of oil each hour on weekends and ngallons each hour on weekdays. How many gallons of oil are burned

Lynna [10]

The question says the machine uses up m gallons of oil each hour on weekends.

This means that if the machine works for 24 hours each day, it implies that:

$\text{Total amount of oil used up in a day = 24}\times m=24m$

There are only two days on weekends i.e. Saturday and Sunday.

This means that if the amount of oil used in 1 day in the weekend is 24m, then we can say:

Saturday: oil used is 24m

Sunday: oil used is 24m

Total oil used during the weekend is:

$24m+24m=48m$

4 0

1 year ago

Y=2x-5<br> 4x-y=7 what is the value of x

amid [387]

Answer:

x=1 and y=-3

Step-by-step explanation:

hope this helped :)

7 0

3 years ago