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3 years ago

The price of a cd was decreased by 20% to £7.68. What was the price before the decrease?

Mathematics

1 answer:

aleksandrvk [35]3 years ago

4 0

Answer:

£9.6

Step-by-step explanation:

x = the original price of a CD

£x = 100% of the original price

The price of a CD was decreased by 20% to £7.68.

This means:

£7.68 = 100% - 20%

£7.68 = 80% of the original price

From this, we will find 1% of the original price.

£7.68 ÷ 80 = 1%

£0.096 = 1%

Since the original price ( x ) = 100% of the original price, we will find 100% of the original price.

£0.096 × 100 = 100%

£9.6 = 100%

Therefore, the original price of a CD = £9.6

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Answer:

$x=7$

Step-by-step explanation:

→ Form an equation

$\frac{x+6+11}{3}=8$

→ Solve

$x+6+11=24\\$

$x=7$

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3 years ago

Suppose you work in the quality assurance department of a chemical processing plant and it is your responsibility to ascertain w

aleksandrvk [35]

Answer:

48.668 ≤ μ ≤ 63.332

Step-by-step explanation:

Given the data:

Sample (X) : 71, 45, 54, 75, 50, 49, 63, 55, 48, 50

Number of samples (n) = 10

α = 95% = 0.05

Determine the range within which the true mean of the fluid samples from the day shift will be with a 95% confidence

True mean = μ

Confidence interval :

m ± t(α/2 ; df) * s/√n

m - t(α/2 ; df) * s/√n ≤ μ ≤ m + t(α/2 ; df) * s/√n

m = sample mean ; s = sample standard deviation ; df = degree of freedom =(n - 1) = (10 - 1) = 9

Calculating the sample mean and standard deviation using calculator to save computation time :

71, 45, 54, 75, 50, 49, 63, 55, 48, 50

m = 56 ; s = 10.25

m - t(0.05/2 ; 9) * s/√n ≤ μ ≤ m + t(0.05/2 ; df) * s/√n

From t table : t(0.05/2 ; 9) = t(0.025, 9) = 2.262

56-2.262 * (10.25/√10) ≤ μ ≤ 56+2.262 * (10.25/√10)

48.668 ≤ μ ≤ 63.332

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Answer:

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Identify the augmented matrix for the system of equations.

lord [1]

Answer:

The augmented matrix for the system of equations is $\left[\begin{array}{cccc}0&2&-3&1\\7&0&5&8\\4&1&-3&6\end{array}\right]$ .

Step-by-step explanation:

This system consists in three equations with three variables ( $x$ , $y$ , $z$ ).The augmented matrix of a system of equations is formed by the coefficients and constants of the system of linear equations. In this case, we conclude that the system of equations has the following matrix:

$\left[\begin{array}{cccc}0&2&-3&1\\7&0&5&8\\4&1&-3&6\end{array}\right]$

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