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3 years ago

(i) Calculate the mean and standard deviation for these weekly incomes.

Mathematics

1 answer:

polet [3.4K]3 years ago

7 0

Answer:

Mean = 272.3

sd = 37.7

Step-by-step explanation:

Mean = sum/n

(221+248+251+255+259+263+264+272+291+297+374) ÷ 11

= 2995/11

= 272.2727273

Variance = (sum of x²)/n - mean²

[(221²+248²+251²+255²+259²+263²+264²+272²+291²+297²+374²)/11] - (2740/11)²

= (831067/11) - (2995/11)²

= 1419.107438

sd² = variance

sd = sqrt(1419.107438)

sd = 37.67104243

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In a certain lottery, you must select 5 numbers (in any order) out of 26 correctly to win. a. How many ways can 5 numbers be

Step2247 [10]

Answer:

a. 7893600

$b.\ \dfrac{1}{26}$

Step-by-step explanation:

Given that there are 26 numbers out of which 5 numbers are to be chosen.

Here repetition is not allowed.

For each of the 5 cases, the total number of possibilities will keep on decreasing by 1.

1st case, number of possibilities = 26

2nd case, number of possibilities = 25

3rd case, number of possibilities = 24

4th case, number of possibilities = 23

5th case, number of possibilities = 22

a. Total number of possibilities = 26 $\times$ 25 $\times$ 24 $\times$ 23 $\times$ 22 = <em>7893600</em>

b. Probability of winning by choosing one number:

Formula for probability of an event E can be observed as: $P(E) = \dfrac{\text{Number of favorable cases}}{\text {Total number of cases}}$

Number of favorable cases = 1

Total number of cases = 26

So, required probability:

$P(E) = \dfrac{1}{26}$

So, the answers are:

a. 7893600

$b.\ \dfrac{1}{26}$

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3 years ago

Jeff worked 4 2/3 hours in the morning and 3 3/4 hours in the afternoon. How many total hours did he work today?

Rainbow [258]

If you would like to know how many total hours did Jeff work today, you can calculate this using the following steps:

4 2/3 hours in the morning + 3 3/4 hours in the afternoon = 4 2/3 + 3 3/4 = 14/3 + 15/4 = 56/12 + 45/12 = (56 + 45) / 12 = 101/12 = 8 5/12 hours

Jeff worked 8 5/12 hours in total.

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2 years ago

X to the power of 2 add 3x

faust18 [17]

Answer:

Hope this helps

Step-by-step explanation:

a) x^2 + 3x = x(x+3)

b) 2x^2 - 8x = 2x(x - 4)

c) 6x + 9x^3 = 3x(2 + 3x^2)

d) 12x^3 - 4x^2 = 4x^2(3x - 1)

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