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3 years ago

What is the area of a circle with a radius of 40 cm? cm² (Use 3.14 for Pi.)

Mathematics

1 answer:

Travka [436]3 years ago

4 0

Answer:5024 cm^2

Step-by-step explanation:

Formula for area of a circle =πr^2

Where π=3.14, r=40cm

Area=3.14*40^2

=3.14*1600

=5024cm^2

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Answer:

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Step-by-step explanation:

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AlladinOne [14]

Answer:

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Step-by-step explanation:

This is an isosceles triangle. Two angles (D and F) are equal because the sides opposite them are equal (or vice versa).

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2 years ago

From past experience, a company has found that in carton of transistors: 92% contain no defective transistors 3% contain one def

jasenka [17]

Answer:

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And replacing we got:

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And the standard deviation is just the square root of the variance and we got:

$Sd(X) = \sqrt{0.3075}= 0.5545$

Step-by-step explanation:

Previous concepts

The expected value of a random variable X is the n-th moment about zero of a probability density function f(x) if X is continuous, or the weighted average for a discrete probability distribution, if X is discrete.

The variance of a random variable X represent the spread of the possible values of the variable. The variance of X is written as Var(X).

Solution to the problem

LEt X the random variable who represent the number of defective transistors. For this case we have the following probability distribution for X

X 0 1 2 3

P(X) 0.92 0.03 0.03 0.02

We can calculate the expected value with the following formula:

$E(X) = \sum_{i=1}^n X_i P(X_i)$

And replacing we got:

$E(X) = 0*0.92 + 1*0.03 +2*0.03 +3*0.02 = 0.1500$

In order to find the variance we need to find first the second moment given by:

$E(X^2) = \sum_{i=1}^n X^2_i P(X_i)$

And replacing we got:

$E(X^2) = 0^2*0.92 + 1^2*0.03 +2^2*0.03 +3^2*0.02 = 0.3300$

The variance is calculated with this formula:

$Var(X) = E(X^2) -[E(X)]^2 = 0.33 -(0.15)^2 = 0.3075$

And the standard deviation is just the square root of the variance and we got:

$Sd(X) = \sqrt{0.3075}= 0.5545$

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vivado [14]

Answer:

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