I’ve been stuck and confused for a little bit. Need help

Oana cheltuiește o sumă de bani în trei zile. În prima zi Oana cheltuiește jumătate din sumă, a

DanielleElmas [232]

Answer:

700 lei

Step-by-step explanation:

You have a geometric sequence for which you know the common ratio and the last term.

There are only three terms, so you can solve the problem in either of two ways.

1. The brute force method (easiest for only a few terms)

Each term is half the one before it, so each term is double the one after it.

3rd term = 100 lei

2nd term = 200

1st term = 400

Total = 700 lei

Oana spent 700 lei

2. Using formulas (best for longer sequences)

The general formula for your sequence is

aₙ = a₁rⁿ⁻¹

For your sequence,

a₃ = 100; r = 0.5

(a) Calculate a₁

Set the last term equal to the general formula.

a₃ = a₁(0.5)ⁿ⁻¹

100 = a₁(0.5)² = 0.25a₁

a₁ = 100/0.25 = 400

(b) Calculate the sum

The general formula for the sum of a geometric sequence is

$\begin{array}{rcl}S_{n}& =& \dfrac{a_{1}(1 - r^{n}) }{ 1 - r}\\\\S_{3}& =& \dfrac{400(1 - 0.5^{3}) }{ 1 - 0.5}\\\\& =& \dfrac{400(1 - 0.125) }{ 0.5}\\\\& =& \dfrac{400\times0.875 }{ 0.5}\\\\& = & \mathbf{700}\\\end{array}$

Oana spent 700 lei.

6 0

3 years ago

suppose you have 76 feet of fencing to enclose a rectangular dog pen. The function A=38x-x^2, where x= width, gives you the area

yan [13]

If A=38x-x^2 then

dA/dx=38-2x

d2A/dx2=-2

Since the acceleration, d2A/dx2 is a constant negative, when velocity, dA/dx=0, it will be an absolute maximum for A(x)

dA/dx=0 only when 38=2x, x=19

A(19)=38(19)-19^2

A(19)=722-361

A(19)=361 ft^2

So the maximum possible area is 361 ft^2

(This will always be true as the maximum possible area enclosed by a given amount of material will always be a perfect square...)

3 0

3 years ago

Please help

Liono4ka [1.6K]

Answer:

P(red) = .3

P(yellow) = .3

75 cubes in the box

Step-by-step explanation:

The probability has to add to 1

Since the number of red cubes equals the number of yellow cubes the probability has to be the same

.4 + x+x = 1

.4 +2x = 1

2x = 1-.4

2x = .6

Divide by 2

x = .6/2

x = .3

P(red) = .3

P(yellow) = .3

We know that

P(blue) = .4 = number of blue cubes/ total number of cubes

.4 = 30/total

total = 30/.4

total = 75

7 0

3 years ago

Four friends are all working in summer jobs. Their names are LaTisha, Zack, Steve and Michelle. The jobs they have found this su

avanturin [10]

Answer:

LatTisha works as a Lifeguard

Zack works as a clerk at a grocery store

Steve works as a food server

Mitchel is a construction worker

Step-by-step explanation:

The parameters of the question are;

The names of the four friends are; LaTisha, Zack, Steve, and Michelle

The jobs found are; Food server, Lifeguard, Construction worker, and Clerk at a grocery store

1. The food server person likes his work

2. Zack and the lifeguard have known each other for years

3. Mitchel and the lifeguard are outside most of the time

4. LaTisha and the person working construction met on their job last summer

5. Neither Zack nor the food server worker worked last summer

We have;

Using known names,

Famale names are; LaTisha and Michelle

Male names are; Steve and Zack

Therefore

The food server worker is a guy, not Zack but likely Steve

Mitchel works outdoors, therefore, she works in the other outdoor employment which is construction

The remaining two occupations are;

Lifeguard and Clerk at a grocery store

Given that Zack is not the lifeguard, we have;

Zack is the clerk at a grocery store

LatTisha is the Lifeguard

6 0

3 years ago

19.

dmitriy555 [2]

Answer:

293 feet per second

Step-by-step explanation:

1056000 feet per hour

1 hour = 60 minutes

1056000 divided by 60 = 17600 feet per minute

1 minute = 60 seconds

17600 divided by 60 = 293 feet per second

5 0

3 years ago