How to do this question plz

Mathematics

1 answer:

ladessa [460]3 years ago

7 0

Answer:

number 4: frequency 8

number 5; frequency 2

Step-by-step explanation:

The mean of all rolls is their sum divided by their number, which is 30. Let x and y represent the number of rolls of 4 and 5, respectively. Then the mean is ...

(1×6 +2×3 +3×5 +4x +5y +6×6)/30 = 3.5

This simplifies to ...

(6 +6 +15 +4x +5y +36) = 3.5×30 . . . . . multiply by 30

4x +5y = 42 . . . . . . subtract 63

Of course, the total number of rolls must be 30:

6 +3 +5 +x +y +6 = 30

x + y = 10

We can solve this system of equations by substitution, using x=10-y:

4(10 -y) +5y = 42

40 +y = 42

y = 2

x = 10 -2 = 8

The two missing numbers are 8 and 2. The frequency of 4 is 8; the frequency of 5 is 2.

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In a pizza takeout restaurant, the following probability distribution was obtained for the number of toppings ordered on a large

Elis [28]

Answer:

The random variable (number of toppings ordered on a large pizza) has a mean of 1.14 and a standard deviation of 1.04.

Step-by-step explanation:

The question is incomplete:

The probability distribution is:

x P(x)

0 0.30

1 0.40

2 0.20

3 0.06

4 0.04

The mean can be calculated as:

$M=\sum p_iX_i=0.3\cdot 0+0.4\cdot 1+0.2\cdot 2+0.06\cdot 3+0.04\cdot 4\\\\M=0+0.4+0.4+0.18+0.16\\\\M=1.14$

(pi is the probability of each class, Xi is the number of topping in each class)

The standard deviation is calculated as:

$s=\sqrt{\sum p_i(X_i-M)^2}\\\\s=\sqrt{0.3(0-1.14)^2+0.4(1-1.14)^2+0.2(2-1.14)^2+0.06(3-1.14)^2+0.04(4-1.14)^2}\\\\s=\sqrt{0.3(-1.14)^2+0.4(-0.14)^2+0.2(0.86)^2+0.06(1.86)^2+0.04(2.86)^2}\\\\ s=\sqrt{0.3(1.2996)+0.4(0.0196)+0.2(0.7396)+0.06(3.4596)+0.04(8.1796)}\\\\s=\sqrt{0.3899+0.0078+0.1479+0.2076+0.3272}\\\\ s=\sqrt{ 1.0804 }\\\\s\approx 1.04$