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3 years ago

4d + 7e = 68 -4 - 6e = -72

Mathematics

1 answer:

Tanzania [10]3 years ago

8 0

Answer:

Step-by-step explanation:

4d + 7e = 68

-4d - 6e = -72

e = -4

4d + 7(-4) = 68

4d - 28 = 68

4d = 96

d = 24

(24, -4)

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Jane must get at least three of the four problems on the exam correct to get an A. She has been able to do 80% of the problems o

NISA [10]

Answer:

a) There is n 81.92% probability that she gets an A.

b) If she gets the first problem correct, there is an 89.6% probability that she gets an A.

Step-by-step explanation:

For each question, there are only two possible outcomes. Either the answer is correct, or it is not. This means that we can solve this problem using binomial distribution probability concepts.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}$

In which $C_{n,x}$ is the number of different combinatios of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And $\pi$ is the probability of X happening.

For this problem, we have that:

The probability she gets any problem correct is 0.8, so $\pi = 0.8$ .

(a) What is the probability she gets an A?

There are four problems, so $n = 4$

Jane must get at least three of the four problems on the exam correct to get an A.

So, we need to find $P(X \geq 3)$

$P(X \geq 3) = P(X = 3) + P(X = 4)$

$P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}$

$P(X = 3) = C_{4,3}.(0.80)^{3}.(0.2)^{1} = 0.4096$

$P(X = 4) = C_{4,4}.(0.80)^{4}.(0.2)^{0} = 0.4096$

$P(X \geq 3) = P(X = 3) + P(X = 4) = 2*0.4096 = 0.8192$

There is n 81.92% probability that she gets an A.

(b) If she gets the first problem correct, what is the probability she gets an A?

Now, there are only 3 problems left, so $n = 3$

To get an A, she must get at least 2 of them right, since one(the first one) she has already got it correct.

So, we need to find $P(X \geq 2)$

$P(X \geq 3) = P(X = 2) + P(X = 3)$

$P(X = 2) = C_{3,2}.(0.80)^{2}.(0.2)^{1} = 0.384$

$P(X = 4) = C_{3,3}.(0.80)^{3}.(0.2)^{0} = 0.512$

$P(X \geq 3) = P(X = 2) + P(X = 3) = 0.384 + 0.512 = 0.896$

If she gets the first problem correct, there is an 89.6% probability that she gets an A.

3 0

3 years ago

Please Help solve this

IgorLugansk [536]

Ok so to find the ratio just do 12/16 = 3/4. that's your common ratio.

The formula for sum of infinite :

a / (1 - r)

a is the first term and r is the ratio

which is

16 / (1 - (3/4))

which is

16 / (1/4)

16 * 4

which is 64

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4 years ago

parking garage a charge A charge $3 per hour for parking. parking garage B charges of a fee of $ 2 pkus $ 2 per hour for parking

I am Lyosha [343]

you good itStep-by-step explanation:

7 0

3 years ago

Read 2 more answers

Can you help me with explanation will give brainiest

Ipatiy [6.2K]

Answer:

Area of rectangular garden = lxb = 10*5

= 50 sq. inch

when area increases by six times

new area = 50*6 = 300 sq inches

now,

let x be increasement in both length and width

(5+x) (10+x) = 300

50 + 5x + 10x + x² = 300

x² + 15x - 250 = 0

x²+ 25x-10x -250 = 0

x(x+25) - 10 (x+25) = 0

( x-10) (x+25) = 0

either x + 25 =0

x = -25 length can be negative

0r x-10 = 0

x = 10

so 10 inches is increase on both side

Step-by-step explanation:

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3 years ago

Tony wants to model the Associative property of addition using a number sentence. Which number sentence could be used for Tonys

FinnZ [79.3K]

A. 12=12
B. 15=15
C.16 = 16
D.15=15

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3 years ago