2x - y = 10

2 answers:

7 0

You can plug -x - 1 for y in the first equation

2x - (-x - 1) = 10

2x + x + 1 = 10

Combine

3x = 9

Divide

x = 3

Plug 3 for x in any equation ( I'll use th second equation )

y = - (3) - 1

y = - 3 - 1 = -4

x = 3 ; y = -4

(3, -4)

cupoosta [38]3 years ago

7 0

2x - y = 10 .............(a)

y = -x - 1 ...........(b)

Substitute y = - x - 1 into equation (a)

2x - y = 10

2x - (-x - 1) = 10

2x + x + 1 = 10

3x + 1 = 10

3x = 10 - 1

3x = 9

x = 9/3 = 3. x = 3

Recall, y = -x - 1 = -3 - 1 = -4

Hence solution (x, y) = (3, -4)

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Answer:

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3 years ago

Suppose that the distribution is bell-shaped. If approximately 99.7% of the lifetimes lie between 568 hours and 1066 hours, then

irakobra [83]

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$\sigma =\frac{478}{6}=79.667$

Step-by-step explanation:

The empirical rule, also referred to as "the three-sigma rule or 68-95-99.7 rule, is a statistical rule which states that for a normal distribution, almost all data falls within three standard deviations (denoted by σ) of the mean (denoted by µ)". The empirical rule shows that 68% falls within the first standard deviation (µ ± σ), 95% within the first two standard deviations (µ ± 2σ), and 99.7% within the first three standard deviations (µ ± 3σ).

And on this case since we are within 3 deviations (because we have 99.7% of the data between 568 and 1066hours), the result obtained using the z score agrees with the empirical rule.

So on this case we can find the standard deviation on this ways:

$\mu -3\sigma = 568$ (1)