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3 years ago

Write a rule for the nth term of the arithmetic sequence described below.

Mathematics

1 answer:

belka [17]3 years ago

7 0

Answer:

an = 115 + (n - 1) (-6)

a25 = - 29

Step-by-step explanation:

We use the definition for the nth term of an arithmetic sequence:

an = a1 + (n - 1) d

a5 = 91 = a1 + (5 - 1) d

91 = a1 + 4 d

a20 = 1 = a1 + (20 - 1) d = a1 + 19 d

1 = a1 + 19 d

now we subtract term by term one expression from the other

90 = 4 d - 19 d

90 = - 15 d

divide both sides by -15 to isolate d

d = 90 / (-15) = -6

Now we can calculate what a1 is using for example:

1 = a1 + 19 d

1 = a1 - 114

add 114 to both sides:

115 = a1

Then our general expression for the sequence is:

an = 115 + (n - 1) (-6)

We can now use it to calculate the value of a25:

a25 = 115 + (24) * (-6) = -29

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A = Ab + Al
Where,
Ab: base area
Al: lateral area
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For the base area:
Ab = (2) * (2)
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4 years ago

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jeyben [28]

Answer:

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Step-by-step explanation:

If S2 is 196 we can divide that by two and get our answer: s=98

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4 years ago

Fish Tales P.O.W.

mars1129 [50]

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3 years ago

A jet ski costs $925 and depreciates by 15% each year. How much will

ivann1987 [24]

Initial cost of the jet ski = $925
Percentage of depreciation per year = 15%
Number of years after which the cost of the jetski has to be determined = 7
Then
Depreciated Value = Initial cost( 1 - percentage of depreciation) ^number of years
      = 925( 1 - 15%)^7
      = 925( 1 - 15/100)^7
      = 925(1 - 0.15)^7
      = 925(0.85)^7
      = 925 *(0.85)^7
      = 925 * 0.3206
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So the depreciated cost of the jet ski after 7 years will be $296.53

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3 years ago

A researcher claims that the variation in the salaries of elementary school teachers is greater than the variation in the salari

guajiro [1.7K]

Answer:

The null hypothesis is $H_o : \sigma^2_1 = \sigma^2 _2$

The alternative hypothesis is $H_a : \sigma_1 ^2 > \sigma^2_2$

$F_{critical} = 1.8608$

$F = 2.9085$

The decision rule is

Reject the null hypothesis

There is sufficient evidence to support the researchers claim

Step-by-step explanation:

From the question we are told that

The first sample size is $n_1 = 30$

The sample variance for elementary school is $s^2_1 = 8324$

The second sample size is $n_2 = 30$

The sample variance for the secondary school is $s^2_2 = 2862$

The significance level is $\alpha = 0.05$

The null hypothesis is $H_o : \sigma^2_1 = \sigma^2 _2$

The alternative hypothesis is $H_a : \sigma_1 ^2 > \sigma^2_2$

Generally from the F statistics table the critical value of $\alpha = 0.05$ at first and second degree of freedom $df_1 = n_1 - 1 = 30 - 1 = 29$ and $df_2 = n_2 - 1 = 30 - 1 = 29$ is