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3 years ago

A card is picked a random from the following set:

Mathematics

1 answer:

lisabon 2012 [21]3 years ago

6 0

Answer:

25%

Step-by-step explanation:

There are 4 cards. Each one is a different number.

Only one card is a 9.

p(9) = 1/4 = 0.25 = 25%

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Use the quadratic formula to find the exact roots of –5x^2 + 8x – 3 = 0. Express your answers as exact roots. Show all steps.

Serjik [45]

Answer:

,jgkhgcjytgxclkgc

Step-by-step explanation:

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2 years ago

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Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.3. (Round your ans

Maurinko [17]

Answer:

0.0039 is the probability that the sample mean hardness for a random sample of 12 pins is at least 51.

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 50

Standard Deviation, σ = 1.3

Sample size, n = 12

We are given that the distribution of hardness of pins is a bell shaped distribution that is a normal distribution.

Formula:

$z_{score} = \displaystyle\frac{x-\mu}{\sigma}$

Standard error due to sampling =

$=\dfrac{\sigma}{\sqrt{n}} = \dfrac{1.3}{\sqrt{12}} = 0.3753$

P(sample mean hardness for a random sample of 12 pins is at least 51)

$P( x \geq 51) = P( z \geq \displaystyle\frac{51 - 50}{0.3753}) = P(z \geq 2.6645)$

$= 1 - P(z < 2.6645)$

Calculation the value from standard normal z table, we have,

$P(x \geq 51) = 1 - 0.9961= 0.0039$

0.0039 is the probability that the sample mean hardness for a random sample of 12 pins is at least 51.

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3 years ago

Solving Simultaneously equations 3. 2x + 3y = 1 -x + 2y = - 4

enot [183]

Answer:

2x5y7

Step-by-step explanation:

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3 years ago

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Need answers to 30 and 31

Mice21 [21]

Answer:

C ; A

Step-by-step explanation:

Question 30:

Perimeter is the sum of all sides.

Perimeter for a recatngle can be found with the formula:

2(L+W)

Length is 7

Width is 4

Plug our values in.

2(7+4)

2(11)

Answer C

Question 31:

Circumference of a circle can be found with the formula:

πd.

Diameter of the given circle is 6.

Plug it in

6π

Round π to 3.14

6(3.14)

18.84

Answer A

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3 years ago

Which must be true of a quadratic function whose vertex is the same as the y-intercept ?

jeka94

A quadratic function whose vertex is the same as the y-intercept has the equation
y=x^2+k (where k is the y-intercept, with vertex (0,k))

Since the vertex coincides with the y-intercept, the axis of symmetry is x=0.

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3 years ago