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2 years ago

A school employs 75 teachers. The following table summarises their length of service at the school,

Mathematics

1 answer:

Over [174]2 years ago

3 0

There are

$12+20+13=45$

female teachers, and

$8+15+7=30$

male teachers.

This means that, out of a total of 75 teachers, 45 are female, leading to a probability of

$\dfrac{45}{75}=\dfrac{3}{5}$

of selecting a female teacher.

If we restrict to those with more than 8 years service, there are 13 female teachers and 7 male teachers.

So, out of a total of 21 teachers, there are 13 female teachers, leading to a probability of

$\dfrac{13}{21}$

of selecting a female teacher.

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The bird house in your friend's yard casts a shadow that is 14 feet long. Your friend is 5 feet tall and casts a shadow that is

astra-53 [7]

3.5/5=14/x 20ft tall

3 0

2 years ago

Supervisor: "Last week, you spoke with 800 customers in 40 hours."

algol13

Answer:12

Step-by-step explanation:

0 0

2 years ago

If you take out a $15,000 loan for a period of 36 months at a 5.4% annual interest rate, how much of your first monthly payment

Tems11 [23]

Answer:

The amount that will go towards the balance is 385.71.

Step-by-step explanation:

The information provided is:

P = Principal of loan = $15,000

r = interest rate = 5.4% p.a. = $\frac{0.054}{12}= 0.0045$

n = number of periods = 36

The amount of the monthly payment that will go towards the balance is:

Amount towards the balance = EMI - Interest

First compute the Equated monthly installments (EMI) as follows:

$EMI=\frac{P\times r\times (1+r)^{n}}{(1+r)^{n}-1} \\=\frac{15000\times0.0045\times(1+0.0045)^{36}}{(1+0.0045)^{36}-1} \\=\frac{79.3125}{0.175}\\=453.21$

Now compute the interest as follows:

$Interest=P\times r\\=15000\times0.0045\\=67.5$

The amount that will go towards the balance is,

Amount towards the balance = EMI - Interest

= 453.21 - 67.5

= 385.71

Thus, the amount that will go towards the balance is 385.71.

4 0

1 year ago

Read 2 more answers

Ann took a taxi home from the airport. The taxi fare was \$2.10$2.10dollar sign, 2, point, 10 per mile, and she gave the driver

Studentka2010 [4]

Answer:

$2.10x+5=49.10$

Distance = 21 miles.

Step-by-step explanation:

Let x be the distance in miles between the airport and Ann's home.

We have been given that Ann took a taxi home from the airport. The taxi fare was $2.10 per mile. So fare for x miles will be 2.10x.

We are also told that she gave the driver a tip of $5. Ann paid a total of $49.10. This means that fare of x miles and tip given to driver equals $49.10. We can represent this information in an equation as:

$2.10x+5=49.10$

Now let us solve our equation.

$2.10x=49.10-5$

$2.10x=44.10$

$x=\frac{44.10}{2.10}=21$

Therefore, the equation $2.10x+5=49.10$ represents the distance in miles between the airport and Ann's home and distance between Ann's home and airport in 21 miles.

3 0

2 years ago

Read 2 more answers

To test whether or not there is a difference between treatments A, B, and C, a sample of 12 observations has been randomly assig

Keith_Richards [23]

Answer:

1. Null hypothesis: $\mu_{A}=\mu_{B}=\mu_{C}$

Alternative hypothesis: Not all the means are equal $\mu_{i}\neq \mu_{j}, i,j=A,B,C$

2. D. 36

3. C. 34

4. B. 1.059

5. B. 8.02

Step-by-step explanation:

Analysis of variance (ANOVA) "is used to analyze the differences among group means in a sample".

The sum of squares "is the sum of the square of variation, where variation is defined as the spread between each individual value and the grand mean"

Part 1

The hypothesis for this case are:

Null hypothesis: $\mu_{A}=\mu_{B}=\mu_{C}$

Alternative hypothesis: Not all the means are equal $\mu_{i}\neq \mu_{j}, i,j=A,B,C$

Part 2

In order to find the mean square between treatments (MSTR), we need to find first the sum of squares and the degrees of freedom.

If we assume that we have $p$ groups and on each group from $j=1,\dots,p$ we have $n_j$ individuals on each group we can define the following formulas of variation:

$SS_{total}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x)^2$

$SS_{between}=SS_{model}=\sum_{j=1}^p n_j (\bar x_{j}-\bar x)^2$

$SS_{within}=SS_{error}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x_j)^2$

And we have this property

$SST=SS_{between}+SS_{within}$

We need to find the mean for each group first and the grand mean.

$\bar X =\frac{\sum_{i=1}^n x_i}{n}$

If we apply the before formula we can find the mean for each group

$\bar X_A = 27$ , $\bar X_B = 24$ , $\bar X_C = 30$ . And the grand mean $\bar X = 27$

Now we can find the sum of squares between:

$SS_{between}=SS_{model}=\sum_{j=1}^p n_j (\bar x_{j}-\bar x)^2$

Each group have a sample size of 4 so then $n_j =4$

$SS_{between}=SS_{model}=4(27-27)^2 +4(24-27)^2 +4(30-27)^2=72$

The degrees of freedom for the variation Between is given by $df_{between}=k-1=3-1=2$ , Where k the number of groups k=3.

Now we can find the mean square between treatments (MSTR) we just need to use this formula:

$MSTR=\frac{SS_{between}}{k-1}=\frac{72}{2}=36$

D. 36

Part 3

For the mean square within treatments value first we need to find the sum of squares within and the degrees of freedom.

$SS_{within}=SS_{error}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x_j)^2$

$SS_{error}=(20-27)^2 +(30-27)^2 +(25-27)^2 +(33-27)^2 +(22-24)^2 +(26-24)^2 +(20-24)^2 +(28-24)^2 +(40-30)^2 +(30-30)^2 +(28-30)^2 +(22-30)^2 =306$

And the degrees of freedom are given by:

$df_{within}=N-k =3*4 -3 = 12-3=9$ . N represent the total number of individuals we have 3 groups each one with a size of 4 individuals. And k the number of groups k=3.

And now we can find the mean square within treatments:

$MSE=\frac{SS_{within}}{N-k}=\frac{306}{9}=34$

C. 34

Part 4

The test statistic F is given by this formula:

$F=\frac{MSTR}{MSE}=\frac{36}{34}=1.059$

B. 1.059

Part 5

The critical value is from a F distribution with degrees of freedom in the numerator of 2 and on the denominator of 9 such that we have 0.01 of the area in the distribution on the right.

And we can use excel to find this critical value with this function:

"=F.INV(1-0.01,2,9)"

And we will see that the critical value is $F_{crit}=8.02$

B. 8.02

5 0

2 years ago