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3 years ago

Please help me answer thanks.

Mathematics

1 answer:

Dmitry_Shevchenko [17]3 years ago

5 0

Answer:

see explanation

Step-by-step explanation:

Given that M is directly proportional to r³ then the equation relating them is

M = kr³ ← k is the constant of proportion

To find k use the condition when r = 4, M = 160, thus

160 = k × 4³ = 64k ( divide both sides by 64 )

2.5 = k

M = 2.5r³ ← equation of variation

(a)

When r = 2, then

M = 2.5 × 2³ = 2.5 × 8 = 20

(b)

When M = 540, then

540 = 2.5r³ ( divide both sides by 2.5 )_

216 = r³ ( take the cube root of both sides )

r = $\sqrt[3]{216}$ = 6

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Asked and answered elsewhere.
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4 years ago

Which equation represents a line that is perpendicular to the line passing through (-4,7) and (1,3)?

diamong [38]

The equation perpendicular to the line passing through the points (-4,7) and (1,3) is $y=\frac{5}{4}x-2$

<h3>Equation perpendicular to a line</h3>

The slope of the given line is calculated as:

$m=\frac{y_2-y_1}{x_2-x_1} \\\\m=\frac{3-7}{1-(-4)} \\\\m=\frac{-4}{5}$

The equation perpendicular to the given line will be of the form

$y-y_1=\frac{-1}{m} (x-x_1)$

Substitute $x_1=-4, y_1=7, and m=\frac{-4}{5}$

$y-7=\frac{5}{4}(x+4)\\\\ y=\frac{5}{4}x+5-7\\\\ y=\frac{5}{4}x-2$

Therefore, the equation perpendicular to the line passing through the points (-4,7) and (1,3) is $y=\frac{5}{4}x-2$

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2 years ago

The perimeter of a triangle is 170 feet and the sides are in the ratio of 25:14:12. Find the area of the triangle.

Viktor [21]

Let
x,y, and z the long sides of the triangle

we know that

x+y+z=170 ft------> equation 1
x/y=25/14----> y=14x/25------> equation 2
y/z=14/12-----> equation 3
x/z=25/12----> z=12x/25------> equation 4

substitute equation 2 and equation 4 in equation 1
x+[14x/25]+[12x/25]=170------> multiply by 25 both sides
25x+14x+12x=4250
51x=4250
x=4250/51
x=250/3
y=14x/25------> y=(250/3)*(14/25)----> y=140/3
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Using Heron's formula,
Area of the triangle = √s (s-a) (s-b) (s-c)
where s is the semiperimeter
s=170/2-----> s=85 ft
Area=√85*[85-250/3]*[85-140/3]*[85-40]
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the answer is
26558.21 ft²

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4 years ago

The local supermarket buys lettuce each day to ensure really fresh produce. Each morning any lettuce that is left from the previ

jekas [21]

Given Information:

Cost price = $4

Selling price = $10

Salvage value = $1.50

Average demand = μ = 250 boxes

Standard deviation = σ = 34 boxes

Required Information:

Number of lettuce boxes = ?

Answer:

The supermarket should purchase 268 boxes of lettuce

Step-by-step explanation:

The required number of lettuce boxes that supermarket should purchase is given by

Number of lettuce boxes = μ + (z*σ)

Where μ is the average demand of lettuce boxes, σ is the standard deviation, and z is the z-score which is given by

p = C_us/(C_us + C_os)

The z-score corresponding to probability p will be obtained.

The cost of under stocking is given by

C_us = Selling price - Cost price

C_us = $10 - $4

C_us = $6

The cost of over stocking is given by

C_os = Cost price - Salvage value

C_os = $4 - $1.50

C_os = $2.50

p = C_us/(C_us + C_os)

p = 6/(6 + 2.50)

p = 0.7058

p = 70.58%

The z-score corresponding to 70.58% probability is approximately 0.54

Number of lettuce boxes = μ + (z*σ)

Number of lettuce boxes = 250 + (0.54*34)

Number of lettuce boxes = 250 + (18.36)

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Number of lettuce boxes ≈ 268

Therefore, the supermarket should purchase 268 boxes of lettuce.

How to use z-table?

Step 1:

In the z-table, find the probability you are looking for and note down the two-digit number of the given row. (e.g 0.5, 2.2, 0.5 etc.)

Step 2:

Then look up at the top of z-table and note down the value in the column for the remaining decimal point in the range of 0.00 to 0.09.

Step 3:

Finally, add the numbers obtained from step 1 and step 2.

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