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3241004551 [841]
3 years ago
5

Eric has been donating books he no longer needs to his local library. After 3 months of donating, he had 157 books left in his r

oom. After 8 months of donating, he had 102 books left in his room. How many books per month did Eric donate on average between months 3 and 8? (2 points)
Mathematics
1 answer:
vladimir1956 [14]3 years ago
6 0
He donated 11 books on average every month
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What would 4(2+x)=18-x equal
matrenka [14]

Answer:

x=2

Step-by-step explanation:

4( 2+x) = 18-x

8 + 4x = 18 - x

4x+x = 18-8

5x= 10

x=2

8 0
4 years ago
Hey guys can you please help me with this math problem?
shusha [124]

Answer:

77777777

Step-by-step explanation:

5 0
3 years ago
Read 2 more answers
A random sample of 49 measurements from one population had a sample mean of 15, with sample standard deviation 5. An independent
kotykmax [81]

Answer:

Comparing the p value with the significance level \alpha=0.01 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, and the difference between the two groups is significantly different.  

Step-by-step explanation:

\bar X_{1}=15 represent the mean for sample 1

\bar X_{2}=18 represent the mean for sample 2

s_{1}=5 represent the sample standard deviation for 1  

s_{f}=6 represent the sample standard deviation for 2  

n_{1}=49 sample size for the group 2  

n_{2}=64 sample size for the group 2  

\alpha=0.01 Significance level provided

t would represent the statistic (variable of interest)  

Concepts and formulas to use  

We need to conduct a hypothesis in order to check if the difference in the population means, the system of hypothesis would be:  

Null hypothesis:\mu_{1}-\mu_{2}=0  

Alternative hypothesis:\mu_{1} - \mu_{2}\neq 0  

We don't have the population standard deviation's, so for this case is better apply a t test to compare means, and the statistic is given by:  

t=\frac{(\bar X_{1}-\bar X_{2})-\Delta}{\sqrt{\frac{s^2_{1}}{n_{1}}+\frac{s^2_{2}}{n_{2}}}} (1)

And the degrees of freedom are given by df=n_1 +n_2 -2=49+64-2=111  

t-test: Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other.

With the info given we can replace in formula (1) like this:  

t=\frac{(15-18)-0}{\sqrt{\frac{5^2}{49}+\frac{6^2}{64}}}}=-2.897

P value

Since is a bilateral test the p value would be:  

p_v =2*P(t_{111}  

Comparing the p value with the significance level \alpha=0.01 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, and the difference between the two groups is significantly different.  

7 0
3 years ago
A cell phone company offers two plans for unlimited calling. The first plan has a monthly charge of $25 and 8.08 per text messag
Alja [10]
The answer is 125 messages.
Firstly the best thing to do is create two different equations.
1. y=25+.08x
2. y=20+.12x
Then you plug into Desmos and see at what point they cross. They cross at (125, 35).
Therefore for 125 text messages would cost 35$ for each plan.
8 0
3 years ago
The area of rectangle is ( 30x²y + 20xy ) cm² and its breadth is 10xy cm .Find its length.
emmasim [6.3K]

Step-by-step explanation:

1) The area of rectangle is ( 30x²y + 20xy ) cm² and its breadth is 10xy cm .Find its length....

= Solution ,

Length ( L ) = ?

breadth ( b ) = 10xy cm

area ( a ) = ( 30x² + 20xy )

Now ,

area ( a ) = l × b

or, ( 30x²y + 20xy ) = L × 10xy cm

or,\frac{30 {xy + 20xy}^{2} }{10xy}  = l \\

or, \: l = 3 {x}^{2 - 1}  + 2cm

\boxed{\sf{l = (3x+2)cm}}

2) Subtract the quotient when 20x⁴y² is divided by 5x³y from the product of 2x and 3y.

= Solution,

= \frac{20 {x}^{4} {y}^{2}  }{5 {x}^{3} y}   \\

= 4xy

The product of 3x and 4y = 6xy

= 6x - 4xy

= \boxed{\sf {2xy}}

hope it helped !!!!

7 0
2 years ago
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