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3 years ago

Devaughn's age is two times Sydney's age. The sum of their ages is 18. What is Sydney's age?

Mathematics

2 answers:

emmainna [20.7K]3 years ago

8 0

Answer:

Sydney's Age is 6

Step-by-step explanation:

6 x 2 = 12

12 + 6 = 18

Lesechka [4]3 years ago

8 0

Answer:

Sydney is 6

Step-by-step explanation:

You get this by dividing 18 by three, as one set of 6 is Sydney while tcice that is her brother.

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Ben walks 25 miles from home to work. If he walks the first 5 miles in 1 hour, the second 5 miles in 1.4 hours, the third 5 mile

natka813 [3]

<u>Answer:</u>

The total time taken to complete 25 miles is 7.6 hours.

Solution:

Ben walks 5 miles in 1 hour,

Second 5 miles in 1.4 hours,

Third 5 miles in 1.7 hours,

Last 5 miles in 1.8 hours

So he walked total 20 miles in (1+1.4+1.7+1.8) hours = 5.9 hours = 6 hours (approximately)

So his average speed is $\left(\frac{20}{6}\right)$ miles/hours = 3.33 miles/hours.

i.e. he travels 3.3 miles in 1 hour,

Then, he travels 1 miles in $\left(\frac{1}{3.3}\right)$ hours

Hence the total time he will take to walk 25 miles is $\left(25 \times\left(\frac{1}{3.3}\right)\right) \text { hours }$ $\Rightarrow \left(\frac{25}{3.3}\right) \text { hours } = 7.5757 hours$

That is approximately 7.57 or 7.6 hours.

8 0

3 years ago

The sum of the first ten terms of a linear sequence is 145. the sum of the next ten term is 445. find the sum of the first four

chubhunter [2.5K]

The sum of the first four terms of the sequence is 22.

In this question,

The formula of sum of linear sequence is

$S_n =\frac{n}{2}(2a+(n-1)d)$

The sum of the first ten terms of a linear sequence is 145

⇒ $S_{10} =\frac{10}{2}(2a+(10-1)d)$

⇒ 145 = 5 (2a+9d)

⇒ $\frac{145}{5} =2a+9d$

⇒ 29 = 2a + 9d ------- (1)

The sum of the next ten term is 445, so the sum of first twenty terms is

⇒ 145 + 445

⇒ $S_{20} =\frac{20}{2}(2a+(20-1)d)$

⇒ 590 = 10 (2a + 19d)

⇒ $\frac{590}{10}=2a+19d$

⇒ 59 = 2a + 19d -------- (2)

Now subtract (2) from (1),

⇒ 30 = 10d

⇒ d = $\frac{30}{10}$

⇒ d = 3

Substitute d in (1), we get

⇒ 29 = 2a + 9(3)

⇒ 29 = 2a + 27

⇒ 29 - 27 = 2a

⇒ 2 = 2a

⇒ a = $\frac{2}{2}$

⇒ a = 1

Thus, sum of first four terms is

⇒ $S_4 =\frac{4}{2}(2(1)+(4-1)(3))$

⇒ $S_4 =2(2+(3)(3))$

⇒ S₄ = 2(2+9)

⇒ S₄ = 2(11)

⇒ S₄ = 22.

Hence we can conclude that the sum of the first four terms of the sequence is 22.

Learn more about sum of sequence of n terms here

brainly.com/question/20385181

#SPJ4

6 0

1 year ago

A firm has the marginal-demand function where D(x)=-1400x÷√25-x² is the number of units sold at x dollars per unit. Find the dem

borishaifa [10]

The equation of the demand function is D(x) = 1400√(25-x²) + 11400

<h3>How to determine the demand function?</h3>

From the question, we have the following parameters that can be used in our computation:

Marginal demand function, D'(x) = -1400x÷√25-x²

Also, we have

D = 17000, when the value of x = 3

To start with, we need to integrate the marginal demand function, D'(x)

So, we have the following representation

D(x) = 1400√(25-x²) + C

Recall that

D = 17000 at x = 3

So, we have

17000 = 1400√(25-3²) + C

Evaluate

17000 = 5600 + C

Solve for C

C = 17000 - 5600

So, we have

C = 11400

Substitute C = 11400 in D(x) = 1400√(25-x²) + C

D(x) = 1400√(25-x²) + 11400

Hence, the function is D(x) = 1400√(25-x²) + 11400