All categories

3 years ago

Find the sum of the first 21 terms of the sequence 5, 9, 13, 17, 21, ... a. 945 c. 947 b. 944 d. 946

2 answers:

6 0

See how the arithmetic sequence is made:
5, 5+4=9, 9+4=13, 13+4=17, ...
So the 21th term will be:
5( first term)+20( n-1 term)•4= 85
And the sum of the first 21 is :
21(5+85)/2= 21•45= 945

DIA [1.3K]3 years ago

4 0

Answer:A 945 is correct

Step-by-step explanation:

You might be interested in

Use the commutative law of MULTIPLICATION to write an equivalent expression.<br><br> 9(x+5)

DochEvi [55]

9x+45
!!!!!!!!!!!!!!!!!!!

6 0

3 years ago

Read 2 more answers

A simple random sample of size nequals81 is obtained from a population with mu equals 83 and sigma equals 27. (a) Describe the

Ivanshal [37]

Answer:

a) $\bar X \sim N (\mu, \frac{\sigma}{\sqrt{n}})$

With:

$\mu_{\bar X}= 83$

$\sigma_{\bar X}=\frac{27}{\sqrt{81}}= 3$

b) $z= \frac{89-83}{\frac{27}{\sqrt{81}}}= 2$

$P(Z>2) = 1-P(Z$

c) $z= \frac{75.65-83}{\frac{27}{\sqrt{81}}}= -2.45$

$P(Z$

d) $z= \frac{89.3-83}{\frac{27}{\sqrt{81}}}= 2.1$

$z= \frac{79.4-83}{\frac{27}{\sqrt{81}}}= -1.2$

$P(-1.2$

Step-by-step explanation:

For this case we know the following propoertis for the random variable X

$\mu = 83, \sigma = 27$

We select a sample size of n = 81

Part a

Since the sample size is large enough we can use the central limit distribution and the distribution for the sampel mean on this case would be:

$\bar X \sim N (\mu, \frac{\sigma}{\sqrt{n}})$

With:

$\mu_{\bar X}= 83$

$\sigma_{\bar X}=\frac{27}{\sqrt{81}}= 3$

Part b

We want this probability:

$P(\bar X>89)$

We can use the z score formula given by:

$z = \frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

And if we find the z score for 89 we got:

$z= \frac{89-83}{\frac{27}{\sqrt{81}}}= 2$

$P(Z>2) = 1-P(Z$

Part c

$P(\bar X$

We can use the z score formula given by:

$z = \frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

And if we find the z score for 75.65 we got:

$z= \frac{75.65-83}{\frac{27}{\sqrt{81}}}= -2.45$

$P(Z$

Part d

We want this probability:

$P(79.4 < \bar X < 89.3)$

We find the z scores:

$z= \frac{89.3-83}{\frac{27}{\sqrt{81}}}= 2.1$

$z= \frac{79.4-83}{\frac{27}{\sqrt{81}}}= -1.2$

$P(-1.2$

8 0

3 years ago

When the following expression is written in simplest form, what is the coefficient of the variable term? -2.5y + 8y - 10.5y

LUCKY_DIMON [66]

Answer:

Option 1 is correct.

-5

Step-by-step explanation:

Given:

The given expression is.

$=-2.5y+8y-10.5y$

Write the given expression in simplest form.

$=-2.5y+8y-10.5y$

Add negative term of y.

$=-13y+8y$

$=-5y$

The simplest form of given expression is $=-5y$

Therefore, the coefficient of the variable term is -5

7 0

3 years ago

Wo runners are saving money to attend a marathon. The first runner has $112 in savings, received a $45 gift from a friend, and w

SpyIntel [72]

Answer:

I believe the last answer is correct

Step-by-step explanation:

Both runners are gaining money

8 0

2 years ago

Math 7 Grade 7

sdas [7]

A and D are Experimental
B and C are Theoretical

Experimental has a specific number of trials like the 11 flips or the classroom of students
Theoretical is based on what is ONLY there like C 3 numbers in a 6 sided die are even 3/6 = .5 = 50%

6 0

3 years ago