A bike shop has bicycles and tricycles in stock. In total he has 21 items in stock with a total of 51 wheels. Can you tell

-2a3 - 3a2 + 4a + 6, 2a3 + 5a2 + 7 <br> sum the expression

zavuch27 [327]

Answer:

2a2 + 4a + 7

Step-by-step explanation:

As, - (2a3 - 3a2 + 4a + 6) + (2a3 + 5a2 + 7)

= 2a2 + 4a + 13

5 0

3 years ago

A survey of 76 commercial airline flights of under 2 hours resulted in a sample average late time for a flight of 2.55 minutes.

nika2105 [10]

Answer:

The best point of estimate for the true mean is:

$\hat \mu = \bar X = 2.55$

$2.55-1.96\frac{12}{\sqrt{76}}=-0.148$

$2.55+1.96\frac{12}{\sqrt{76}}=5.248$

Since the time can't be negative a good approximation for the confidence interval would be (0,5.248) minutes. The interval are tellling to us that at 95% of confidence the average late time is lower than 5.248 minutes.

Step-by-step explanation:

Information given

$\bar X=2.55$ represent the sample mean for the late time for a flight

$\mu$ population mean

$\sigma=12$ represent the population deviation

n=76 represent the sample size

Confidence interval

The best point of estimate for the true mean is:

$\hat \mu = \bar X = 2.55$

The confidence interval for the true mean is given by:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

The Confidence level given is 0.95 or 95%, th significance would be $\alpha=0.05$ and $\alpha/2 =0.025$ . If we look in the normal distribution a quantile that accumulates 0.025 of the area on each tail we got $z_{\alpha/2}=1.96$

Replacing we got:

$2.55-1.96\frac{12}{\sqrt{76}}=-0.148$

$2.55+1.96\frac{12}{\sqrt{76}}=5.248$

Since the time can't be negative a good approximation for the confidence interval would be (0,5.248) minutes. The interval are tellling to us that at 95% of confidence the average late time is lower than 5.248 minutes.

7 0

3 years ago

Pablo runs 1.5 miles on his first day of training for a road race the next day he increases his distance run by 0.5 miles the da

Sati [7]

So, he runs 1.5 then adds 0.5 every day,
1.5
(1.5+0.5)+1.5=x
(2.0+0.5)+x=z
2.5+0.5+z=y
etc.
Why, they want to know the total distance he runs, so thats why you add x,y,z to the end, and you add 2.0+0.5 because he adds 0.5 every dat Plus the other day's miles jogged

8 0

3 years ago

Read 2 more answers

3x -4y= -20 -x +2y =10 whats the value of y

Anni [7]

3x-4y=10
-20-x+2y=10 then -30+2y=x now plug this in the other equation:
3(-30+2y)-4y=10
-90+6y-4y=10
2y=100
y=50

4 0

2 years ago

Please tell me what this is

Harlamova29_29 [7]

Answer:7.2+z=10

Step-by-step explanation:if I am right you just have to do the equacion

4 0

2 years ago