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2 years ago

4b) Work out the mean and standard deviation of the following: picture included

Mathematics

1 answer:

Jlenok [28]2 years ago

4 0

Answer:

Yes, your simultaneous equations are correct;

Solve them like so:

170 + 1.6449σ = 180 - 0.8416

2.4865σ = 10

σ = 4.0217...

μ = 170 + 1.6449(4.0217...)

μ = 176.615...

MS is correct, you must've made an error in solving or rearranging

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Step-by-step explanation:

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3 years ago

Read 2 more answers

Help me plz, i’d love u forever

Sergio039 [100]

1. We know that 1 feet = 12 inches

let x be a number of inches, which when added to 18 inches will give 7 feet

18 inches + x inches = 7 feet

18 inches + x inches = 84 inches [1 feet = 12 inches]

x inches = 84 inches - 18 inches

x inches = 66 inches

2. We know that 1 mile = 1760 yards

let x be the number of yards, when added to 2000 yards will be equal to 2 miles

2000 yards + x yards = 2 miles

2000 yards + x yards = 3520 yards

x yards = 1520 yards

3. We know that 1 feet = 12 inches

Number of feet = Given number of inches / 12

Number of feet = 108 / 12

Number of feet = 9 ft.

4. We know that 1 mile = 5280 feet

let x be the number of feet, when added to 8800 feet. will be equal to 8 miles

8800 feet + x feet = 8 miles

8800 feet + x feet = 42240 feet [1 mile = 5280 feet]

x feet = 42240 - 8800

x feet = 33440 ft.

5. We know that 12 inches = 1 feet

let x be the number of inches, when added to 37 inches, will be equal to 5 feet

37 inches + x inches = 5 feet

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6. We know that 1 yard = 3 feet

So, (number of yards)*3 = (number of feet)

Number of yards = number of feet / 3

Number of yards = 73 / 3 = 24.33 yards

7. We know that 1 yard = 3 feet

let x be the number of feet added to 15 feet to make 9 yards

15 feet + x feet = 9 yards

15 feet + x feet = 27 feet [1 yard = 3 feet]

x feet = 12 ft

8. We know that 1 mile = 1760 yards

let x be the number of yards remaining to reach 4 miles

3000 yards + x yards = 4 miles

3000 yards + x yards = 7040

x yards = 4040 yards

9. We know that 1 yard = 3 feet

So, number of yards * 3 = number of feet

replacing the values:

number of yards*3 = 114

number of yards = 114/3

number of yards = 38 yards

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x feet + 9000 feet = 3 miles

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x ft = 6840 ft

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let x be the number of inches that must be added to 46 inches to get a length of 9 feet

46 inches + x inches = 9 feet

46 inches + x inches = 108 inches

x inches = 108 - 46 inches

x inches = 62 inches

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let x be the number of yards that must be added to 3500 yards to make 2 miles

3500 yards + x yards = 2 miles

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number of feet = number of inches / 12

number of feet in 252 inches

Number of feet = 252/12

Number of feet = 21 ft

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x ft + 6500 ft = 2 miles

x ft + 6500 ft = 10560 ft

x ft = 4060 ft

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3 years ago

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Alex787 [66]

Try x = 65
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3 years ago

Triangle A C D is shown. A line is drawn from point D to point B on side A C to form a right angle. Line A D is labeled s. The l

devlian [24]

Answer:

s = 17units

Step-by-step explanation:

For this problem, we are trying to find a specific unknown side length.

We're actually given some extraneous information (information that is not needed to solve the problem): It isn't necessary to know that BC is 5.

If the side AD with the unknown length is part of a right triangle (the triangle in red in the attached diagram), we can use the Pythagorean Theorem to solve for AD.

It isn't clear if the diagram you were provided gives ∠ABD as a right angle, if it only gives ∠CBD as a right angle, or if it gives both as a right angle. Below, we prove that it doesn't matter, because regardless, both must be right angles.

Is Triangle ABD a "right triangle"?

Since B is between A and C, then the two angles ∠ABD & ∠CBD form a linear pair, and by the linear pair postulate are supplementary. Since they are supplementary, their measures add to 180°. Using the fact that all right angles are 90°, substitution, the subtraction property of equality, arithmetic, the measure of ∠ABD is also 90°, and thus must be a right angle. Thus, based on the given information, both ∠ABD & ∠CBD must be right angles.

Consequently, triangle ABD is a right triangle, by definition (it is a triangle that has a right angle).

Pythagorean Theorem

Since triangle ABD is a right triangle, the Pythagorean Theorem can be applied.

The Pythagorean Theorem states that $a^{2} +b^{2} =c^{2}$ where "c" is the hypotenuse (the side across from the right angle) and "a" and "b" the the lengths of the two other sides (called legs) of the right triangle. (Aside: Because of the commutative property of addition, it doesn't matter which of the two legs' lengths is used for a, and which is used for b. The only thing that is required is that "c" be the length of the hypotenuse)

In our triangle, side AD, with unknown length "s" is the length of our hypotenuse, and sides AB and BD are the two legs. Substituting values into the Pythagorean Theorem equation, we can solve for the unknown "s":

$a^{2} +b^{2} =c^{2}$

$(8)^{2} +(15)^{2} =(s)^{2}$