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kifflom [539]
2 years ago
9

George still has 40 percent of his book to read. If George has read 180 pages, how many pages does he still have to read? How do

you know?
Mathematics
1 answer:
beks73 [17]2 years ago
5 0

Answer:  72

Step-by-step explanation:    so you do a line = line method the lines should look like they are fractions.  

you do it for the both numbers the percent is always out of 100.

it should look like this

40%            ?

--------- = -----------    

100%       180

then you cross multiply 40 and 180 and than divide it by 100.   your answer should be 72.    you later replace the ? with 72

you know this because It is smaller than 180 and its bigger than the number 40.

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The time between failures for an electrical appliance is exponentially distributed with a mean of 25 months. What is the probabi
katrin [286]

Answer:

The probability that the next failure will not occur before 30 months have elapsed is 0.0454

Step-by-step explanation:

Using Poisson distribution  where

t= number of units of time

x= number of occurrences in t units of time

λ= average number of occurrences per unit of time

P(x;λt) = e raise to power (-λt)  multiplied by λtˣ divided by x!

here λt = 25

x= 30

P(x= 30) = 25³⁰e⁻²⁵/ 30!

P (x= 30) = 8.67 E41 * 1.3887 E-11/30!    (where E= exponent)

P (x=30) = 1.204 E31/30!

Solving it with a statistical calculator would give

P (x=30) = 0.0454

The probability that the next failure will not occur before 30 months have elapsed is 0.0454

7 0
2 years ago
What is the selling price of an item if the original cost is $784.50 and the markup on the item is 6.5 percent?
kotegsom [21]

Answer:

835.49

Step-by-step explanation:

selling price = original cost + markup value

We need to find the markup

markup = original cost * markup percent

             = $784.50 * 6.5%

           = $784.50 *.06.5

           =50.9925

Rounding to the nearest cent

            =50.99

selling price = original cost + markup value

                     =784.50+50.99

                      835.49

6 0
2 years ago
If the inflation rate is positive, purchasing power . This situation is reflected in the rate of return on an investment, which
kirill [66]

Answer:

If inflation rate is positive, purchasing power of money decreases thus the rate of returns on investment decreases.

Step-by-step explanation:

When the prices of goods and services are averagely increasing we say that inflation is positive.Purchasing power is high when a currency value is able to purchase more goods and services as per unit of money can buy.when inflation is positive, the amounts of goods and services that can be purchased is reduced.

6 0
2 years ago
Assume the blood pressures of 10 people were measured before and after sleeping for the night. What is the corresponding critica
NeX [460]

Answer:

For the critical value we need to calculate the degrees of freedom given by:

df = n-1= 10-1=9

And since we have a one tailed test we need to look in the t distribution with 9 degrees of freedom a quantile who accumulates 0.05 of the area on a tail and we got:

|t_{crit}| =1.833

Step-by-step explanation:

Previous concepts

A paired t-test is used to compare two population means where you have two samples in which observations in one sample can be paired with observations in the other sample. For example if we have Before-and-after observations (This problem) we can use it.  

Let put some notation  

x=test value with right arm , y = test value with left arm  

The system of hypothesis for this case are:  

Null hypothesis: \mu_y- \mu_x = 0  

Alternative hypothesis: \mu_y -\mu_x \neq 0  

The first step is calculate the difference d_i=y_i-x_i

The second step is calculate the mean difference  

\bar d= \frac{\sum_{i=1}^n d_i}{n}= \frac{361}{5}  

The third step would be calculate the standard deviation for the differences, and we got:  

s_d =\frac{\sum_{i=1}^n (d_i -\bar d)^2}{n-1}  

The 4 step is calculate the statistic given by :  

t=\frac{\bar d -0}{\frac{s_d}{\sqrt{n}}}  

For the critical value we need to calculate the degrees of freedom given by:

df = n-1= 10-1=9

And since we have a one tailed test we need to look in the t distribution with 9 degrees of freedom a quantile who accumulates 0.05 of the area on a tail and we got:

|t_{crit}| =1.833

5 0
2 years ago
Suppose the area of a circle is 254.4696 square inches. Whats the radius of the circle? Use pie=3.1416. A. 18 in B. 81 in. C. 9
andrezito [222]

Answer:

radius = 9 inches

Step-by-step explanation:

Area = \pi r^{2}

r = radius

Area = 254.4696 square inches

so we have:

r^{2} = \frac{A}{\pi} \\\\r = \sqrt{\frac{A}{\pi}} \\\\r = \sqrt{\frac{254.4696}{3.1416}} \\\\r = \sqrt{81}

so we have: r = 9 inches

6 0
2 years ago
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