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natka813 [3]
3 years ago
15

Elevii clasei a IV-a se informeaza despre preturile unor obiecte:3 aparate foto de acelasi fel si un laptop costa 2700lei,iar 5

aparate foto si 2 laptopuri,de acelasi fel ca primele costa,4900lei.Cat costa un aparat foto?Dar un laptop?Prin metoda compaatiei va rog !!!!!!! URGENT !!!!!!
Mathematics
1 answer:
kipiarov [429]3 years ago
5 0
Laptops are 1200 each and cameras are 500 each.

Using elimination:
3c+l=2700
5c+2l=4900

We will make the coefficients of l the same by multiplying the top equation by 2:
2(3c+l=2700)
6c+2l=5400

Our system is now
6c+2l=5400
5c+2l=4900

Subtract the bottom equation:
6c+2l=5400
-(5c+2l=4900)

We have
1c=500
So each camera is 500.

Substitute that in our original first equation:
3(500)+l=2700
1500+l=2700
1500+l-1500=2700-1500
l=1200
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A shipment of 40 fancy calculators contains 3 defective units. What is the probability if a college bookstore buys 20 calculator
JulsSmile [24]

Answer:

38.46%

Step-by-step explanation:

There are no names or marking that can make the calculator look different, so the order is not important. Then we should use a combination to solve this problem.

There are 40 calculators in one shipment, 37 of them good items and 3 of them are defect items. We need to choose 19 good calculators and 1 defect calculator. The number of ways to do that will be:

\frac{37}{19}* \frac{3}{1}= 37!\frac{37!}{19!(37-19!)} * \frac{3!}{1!(3-1)!}= 53017895700

The number of possible ways to choose 20 calculators out of 40 calculators will be:

\frac{40}{20}= \frac{40!}{20!(40-20!)}=137846528820

The chance will be: 53017895700/ 137846528820 = 0.3846= 38.46%

4 0
3 years ago
I forgot how to solve these. Please help.
AnnyKZ [126]
This is the answer for both number 9 and number 11.
Good luck

6 0
3 years ago
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Luiza is jumping on a trampoline. Ht models her distance above the ground (in m) t seconds after she starts
Damm [24]

Answer:

t=2.08 seconds.

Step-by-step explanation:

Well, in this example, H(t)=-0.6cos(2pi/2.5)t+1.5 should be equal to 1.2. If calculated, -0.6cos(0.8pi)t=1.2-1.5 which is equal to -0.6cos(0.8pi)t=-0.3, then cos(0.8pi)t=0.5. The value of cosine in terms of radians when it is equal to 0.5 is pi/3. So, cos(0.8pi)t=cos(pi/3). If simplified, (0.8pi)*t=5pi/3. pi's are cancelled out and t is calculated as 2.08333... If rounded to the nearest hundredth it is 2.08.

4 0
2 years ago
What is the interval notation for the compound inequality? x ≤ −4 or x ≥ 5
torisob [31]

Answer:

(-∞, -4] ∪ [5, ∞)

Step-by-step explanation:

Hi!

Alright, so greater (or less) than or equal to is denoted with a bracket.

If x is less than or equal to -4, then the bracket is on the left side.

(___, -4]

Because x is <em>any</em> number under or equal to -4, x can range from negative infinity. However, we use a parentheses for infinity because infinity can never truly be reached.

So, x \leq -4 = (-∞, -4]

X\geq5

Equal to = bracket

X is any number above 5, so

[5, ∞)

Because we want both of these, we use the union sign (∪)

so,

= (-∞, -4] ∪ [5, ∞)

8 0
3 years ago
Which statements are true? Check all that apply.
Dvinal [7]

Answer:

3is the answer because t

s apply

Step-by-step explanation:

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