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3 years ago

Find the common ratio and the explicit formula -3, 9, -27, 81,

Mathematics

1 answer:

Fofino [41]3 years ago

6 0

Answer:

see explanation

Step-by-step explanation:

These are the terms of a geometric sequence with n th term

$a_{n}\\$ = a $(r)^{n-1}$

where re a is the first term and r the common ratio

r = 9 ÷ - 3 = - 27 ÷ 9 = 81 ÷ - 27 = - 3 ← common ratio

and a = - 3, thus

[te x]a_{n}[/tex] = - 3 $(-3)^{n-1}$ ← explicit formula

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Gelneren [198K]

Answer:

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Step-by-step explanation:

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2 years ago

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A researcher compares the effectiveness of two different instructional methods for teaching physiology. A sample of 178 students

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Answer:

critical value = 1.645

The 90% confidence interval = ( -22.62, -17.58)

Step-by-step explanation:

Given that:

the sample size $n_1$ = 178

the sample size $n_2$ = 226

the sample mean $\overline x_1$ = 54.4

the sample mean $\overline x_2$ = 74.5

population standard deviation $\sigma_1$ = 18.58

population standard deviation $\sigma_2$ = 9.52

level of significance ∝ = 1 - 0.90 = 0.10

The critical value for $Z_{\alpha/2} = Z _{0.10/2} = Z_{0.005}$ is 1.645

For the construction of our confidence interval, we use 90% since that is used to find the critical value.

∴

The margin of error = $Z \times\sqrt{\dfrac{\sigma_1^2}{n_1} + \dfrac{\sigma_2^2}{n_2}}$

$1.645 \times\sqrt{\dfrac{18.58^2}{178} + \dfrac{9.52^2}{226}}$

$1.645 \times\sqrt{\dfrac{345.2164}{178} + \dfrac{90.6304}{226}}$

$1.645 \times\sqrt{2.34042}$

$\simeq$ 2.52

The lower limit = $( \overline x_1 - \overline x_2) - (M.O.E)$

= ( 54.4-74.5) - (2.52)

= -20.1 - 2.52

= -22.62

The upper limit = $( \overline x_1 - \overline x_2) + (M.O.E)$

= ( 54.4-74.5) + (2.52)

= -20.1 + 2.52

= -17.58

The 90% confidence interval = ( -22.62, -17.58)

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Find the common ratio and the explicit formula -3, 9, -27, 81,​

Find the common ratio and the explicit formula -3, 9, -27, 81,