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11Alexandr11 [23.1K]

3 years ago

14

Is there an error in this statement If x2 = 25, then x = 5.

2 answers:

katen-ka-za [31]3 years ago

7 0

Yes there is an error in this statement.

because x^2 = 25
so x = 5...this is one condition

Another condition is x = -5
(-5)^2 = 25 (this is also true)

Troyanec [42]3 years ago

3 0

No because 5 to the power of 2 equals 5 x 5 and 5 x 5 = 25 hope this helped

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An automobile company wants to determine the average amount of time it takes a machine to assemble a car. A sample of 40 times y

aksik [14]

Answer:

A 98% confidence interval for the mean assembly time is [21.34, 26.49] .

Step-by-step explanation:

We are given that a sample of 40 times yielded an average time of 23.92 minutes, with a sample standard deviation of 6.72 minutes.

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

P.Q. = $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ ~ $t_n_-_1$

where, $\bar X$ = sample average time = 23.92 minutes

s = sample standard deviation = 6.72 minutes

n = sample of times = 40

$\mu$ = population mean assembly time

<em> Here for constructing a 98% confidence interval we have used a One-sample t-test statistics because we don't know about population standard deviation. </em>

<u>So, a 98% confidence interval for the population mean, </u> $\mu$ <u> is; </u>

P(-2.426 < $t_3_9$ < 2.426) = 0.98 {As the critical value of z at 1% level

of significance are -2.426 & 2.426}

P(-2.426 < $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ < 2.426) = 0.98

P( $-2.426 \times {\frac{s}{\sqrt{n} } }$ < ${\bar X-\mu}$ < $2.426 \times {\frac{s}{\sqrt{n} } }$ ) = 0.98

P( $\bar X-2.426 \times {\frac{s}{\sqrt{n} } }$ < $\mu$ < $\bar X+2.426 \times {\frac{s}{\sqrt{n} } }$ ) = 0.98

<u>98% confidence interval for</u> $\mu$ = [ $\bar X-2.426 \times {\frac{s}{\sqrt{n} } }$ , $\bar X+2.426 \times {\frac{s}{\sqrt{n} } }$ ]

= [ $23.92-2.426 \times {\frac{6.72}{\sqrt{40} } }$ , $23.92+2.426 \times {\frac{6.72}{\sqrt{40} } }$ ]

= [21.34, 26.49]

Therefore, a 98% confidence interval for the mean assembly time is [21.34, 26.49] .

7 0

3 years ago

Force is giving away tickets to a school play. She gives away 20 more adult tickets than children's tickets. She gives away 3 ti

swat32

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hope that helps :))

8 0

3 years ago

Is the relation shown in the arrow diagram a function? Explain. *<br> (NEED HELP ASAP)

Paraphin [41]

Answer:

It is a function.

Step-by-step explanation: Each input has only one output.

4 0

3 years ago

Work out the following giving your answers in their simplest form 2/7 ÷ 3/4

Usimov [2.4K]

Answer:

8/21

Step-by-step explanation:

2/7 ÷ 3/4

2/7 * 4/3

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3 years ago

An airplane can cruise at 570 mph. How far can it fly in 4/3 hours?

cestrela7 [59]

Answer:

The plane can fly 760 miles in 4/3 hours.

Step-by-step explanation:

Given that:

An airplane can cruise at 570 miles per hour.

We have to find the distance travelled by train in 4/3 hours.

Distance = Speed * Time

Distance = $570*\frac{4}{3}$

Distance = $\frac{2280}{3}$

Distance = 760 miles

Hence,

The plane can fly 760 miles in 4/3 hours.

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3 years ago