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tester [92]
3 years ago
8

There are 15 boys and 10 girls in a hall, each holding coins in their hand.The mean number of coins for the children is 10 The m

ean number of coins for the boys is 8Work out the mean number of coins for the girls.
Mathematics
1 answer:
DiKsa [7]3 years ago
6 0

Answer:

13 coins

Step-by-step explanation:

There are 25 kids in total.

The fraction of kids that are boys and girls are:

B=\frac{15}{25}=0.6\\B=\frac{10}{25}=0.4

The mean number of coins for all kids is given by:

M=B*M_B+G*M_G

If we are given that M = 10, and MB = 8, then the mean number of coins for the girls is:

10=0.6*8+0.4*M_G\\M_G=\frac{10-4.8}{0.4}\\M_G=13\ coins

The mean number of coins for the girls is 13.

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Here is a simple probability model for multiple-choice tests. Suppose that each student has probability p of correctly answering
Alla [95]

Answer:

a) The probability that Jodi scores 78% or lower on a 100-question test is 4%.

b) The probability that Jodi scores 78% or lower on a 250-question test is 0.023%.

Step-by-step explanation:

a) To approximate this distribution we have to calculate the mean and the standard distribution.

The mean is the proportion p=0.85.

The standard deviation can be calculates as:

\sigma=\sqrt{\frac{p(1-p)}{n} }= \sqrt{\frac{0.85*(1-0.85)}{100} }=0.04

To calculate the probability that Jodi scores 78% or less on a 100-question test, we first calculate the z-value:

z=\frac{p-p_0}{\sigma} =\frac{0.78-0.85}{0.04} =-1.75

The probability for this value of z is

P(x

The probability that Jodi scores 78% or lower on a 100-question test is 4%.

b) In this case, the number of questions is 250, so the standard deviation needs to be calculated again:

\sigma=\sqrt{\frac{p(1-p)}{n} }= \sqrt{\frac{0.85*(1-0.85)}{250} }=0.02

To calculate the probability that Jodi scores 78% or less on a 250-question test, we first calculate the z-value:

z=\frac{p-p_0}{\sigma} =\frac{0.78-0.85}{0.02} =-3.5

The probability for this value of z is

P(x

The probability that Jodi scores 78% or lower on a 250-question test is 0.023%.

6 0
2 years ago
THIS IS DUE IN 10 MIN!!
AVprozaik [17]
The discount is 50-14 = $36

% discount = (36/50)*100 = 72%
6 0
3 years ago
Solve for x xx: 7 x + 4 9 ∘ 7x+49 ​∘ ​​ 2 x + 9 4 ∘ 2x+94 ​∘ ​​
Murrr4er [49]
The value for x is 9 because:

7x +49 = 2x + 94
7x-2x=45
5x=45
x=45/5
x=9
6 0
3 years ago
Use Euler’s Formula to find the missing number.<br> Edges: 37<br> Faces: 25<br> Vertices: ?
matrenka [14]

Answer:

Step-by-step explanation:

Comment

The formula that relates edges faces and vertices is  F + V = E + 2

Givens

Edges (E): 37

Faces (F) = 25

Vertices: x

Solution

25 + x = 37 + 2                Subtract 25 from both sides.

25-25 +x= 37 - 25 + 2    Combine

x = 12 + 2

x = 14

Answer: The vertices =<u> 14</u>

7 0
2 years ago
The production cost for a t-shirt printing company is a function of the number of t-shirts that are printed, t. The function tha
uranmaximum [27]

Answer:

Therefore the company have to print either 47 or 12 t-shirt for its production cost to be $40 or less.

Step-by-step explanation:

Given that,

The function that models the production cost is

f(t)=0.1 t^2-6t+100

To find the number of t-shirt, we put f(t)=40 in given function.

∴40= 0.1t²-6t+100

⇒ 0.1t²-6t+100-40=0

⇒0.1 t²- 6t +60=0

⇒t²-60t+600=0

Applying quadratic formula x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}, a=1, b= - 60 and c=600

t=\frac{-(-60)\pm\sqrt{(-60)^2-4.1.600}}{2.1}

  = 47.32,12.67

 ≈47, 12

Therefore the company have to print either 47 or 12 t-shirt for its production cost to be $40 or less.

7 0
3 years ago
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