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Elena L [17]
3 years ago
10

A car is traveling at a rate of

Mathematics
2 answers:
Tomtit [17]3 years ago
8 0
63/60 = 1.05 km/min
1.05 * 20 = 21 km/20min
Oxana [17]3 years ago
3 0
63/60min = 1.05k per min
(1.05k/min) * (20min) = 21k
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The tensile strength of stainless steel produced by a plant has been stable for a long time with a mean of 72 kg/mm2 and a stand
Elanso [62]

Answer:

95% confidence interval for the mean of tensile strength after the machine was adjusted is [73.68 kg/mm2 , 74.88 kg/mm2].

Yes, this data suggest that the tensile strength was changed after the adjustment.

Step-by-step explanation:

We are given that the tensile strength of stainless steel produced by a plant has been stable for a long time with a mean of 72 kg/mm 2 and a standard deviation of 2.15.

A machine was recently adjusted and a sample of 50 items were taken to determine if the mean tensile strength has changed. The mean of this sample is 74.28. Assume that the standard deviation did not change because of the adjustment to the machine.

Firstly, the pivotal quantity for 95% confidence interval for the population mean is given by;

                         P.Q. = \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }  ~ N(0,1)

where, \bar X = sample mean strength of 50 items = 74.28

            \sigma = population standard deviation = 2.15

            n = sample of items = 50

            \mu = population mean tensile strength after machine was adjusted

<em>Here for constructing 95% confidence interval we have used One-sample z test statistics as we know about population standard deviation.</em>

So, 95% confidence interval for the population mean, \mu is ;

P(-1.96 < N(0,1) < 1.96) = 0.95  {As the critical value of z at 2.5% level of

                                                  significance are -1.96 & 1.96}  

P(-1.96 < \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } } < 1.96) = 0.95

P( -1.96 \times {\frac{\sigma}{\sqrt{n} } } < {\bar X-\mu} < 1.96 \times {\frac{\sigma}{\sqrt{n} } } ) = 0.95

P( \bar X-1.96 \times {\frac{\sigma}{\sqrt{n} } } < \mu < \bar X+1.96 \times {\frac{\sigma}{\sqrt{n} } } ) = 0.95

<u><em>95% confidence interval for</em></u> \mu = [ \bar X-1.96 \times {\frac{\sigma}{\sqrt{n} } } , \bar X+1.96 \times {\frac{\sigma}{\sqrt{n} } } ]

                 = [ 74.28-1.96 \times {\frac{2.15}{\sqrt{50} } } , 74.28+1.96 \times {\frac{2.15}{\sqrt{50} } } ]

                 = [73.68 kg/mm2 , 74.88 kg/mm2]

Therefore, 95% confidence interval for the mean of tensile strength after the machine was adjusted is [73.68 kg/mm2 , 74.88 kg/mm2].

<em>Yes, this data suggest that the tensile strength was changed after the adjustment as earlier the mean tensile strength was 72 kg/mm2 and now the mean strength lies between 73.68 kg/mm2 and 74.88 kg/mm2 after adjustment.</em>

8 0
3 years ago
Select all number combinations that COULD make a triangle
tester [92]

Answer:

2 cm, 9 cm, 10 cm

Step-by-step explanation:

To know if a combination is a triangle all you have to do is see if the combinations add up to 180

(2)(9)(10)=180 therefore it is a triangle.

All the other angles do not add up to 180 so they can't be triangles!!

(4)(10)(3) =120

(5)(6)(11) =330

(4)(5)(7) =140

4 0
2 years ago
A tour company has a boat that sits at most 40 passengers. For a cruise on the Hudson River they charge $12 per adult and $5 per
EleoNora [17]

Answer:

No

Step-by-step explanation:

For the adults:

$12 times the 14 adults which is: $168

Then for the kids:

$5 times the 9 kids which is: $45

Add next:

$168 plus the $45 equals $213

A(14)+b(5)=c

5 0
3 years ago
Raja drew a circle and labeled the center S. He used the expression 12. to find the
Aleonysh [2.5K]

Answer:a

Step-by-step explanation:

5 0
3 years ago
Please help simple pre algebra!!!​
xxMikexx [17]
C=pi(d)

So d=7ft

Then pi(7ft)=21.98
3 0
3 years ago
Read 2 more answers
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