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timurjin [86]
3 years ago
6

g Four distinct numbers are to be selected from the list {−5, −4, −3, −2, −1, 1, 2, 3, 4}. In how many ways can this selection b

e done so that the product of the four numbers is positive?
Mathematics
1 answer:
ahrayia [7]3 years ago
5 0

Answer: 66 possible combinations.

Step-by-step explanation:

To have a positive product we have 3 situations.

The 4 numbers are positive:

if the "order" of the selection does not matter, then we have only one solution here:

1, 2, 3 and 4.

Second case, we have two negative numbers and two positive numbers.

Here we can use the fact that in a group of N objects, the number of different combinations of K objects (where K ≤ N) is:

C = \frac{N!}{(N -K)!*K!}

Here we have 5 negative numbers and we want to make groups of 2, so the possible combinations are:

C = \frac{5!}{3!*2!} = \frac{5*4}{2*1} = 2*5 = 10

And we have exactly the same for the other two positive numbers, but in this case we have N = 4 and  K = 2.

C = \frac{4!}{2!*2!}  = 6

The total number of combinations is the product of those two:

C = 10*6 = 60 combinations

Now, the last option is that the 4 numbers are negative numbers, so here we have 5 negative numbers and we want to make groups of 4.

C = \frac{5!}{1!*4!} = 5

So in total, we have: 1 + 60 + 6 = 66 possible combinations.

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You have invested in three different stocks: Engineering Aces, Upton Clothiers, and Thompson Musical Instruments. Because you ha
Serga [27]

Answer:

answer is 0.001254.

Step-by-step explanation:

Given that you invested in 3 stocks of Engineering Aces, Upton Clothiers, and Thompson Musical Instruments.

Also given that each stock value is independent of the other.

Let E be the event changing in value by more than 10% in a given week for Engineering Aces,

U be the event changing in value by more than 10% in a given week for Upton Clothiers, and T be the event changing in value by more than 10% in a given week for Thompson Musical Instruments.

Given that P(E) =  = 19%

P(U) = 11%

P(T) = 6%

probability that all three will change by more than 10% in the same week

= P(EUT)

= P(E) P(U) P(T) since three events are independent.

=0.19(0.11)0.06

= 0.001254



8 0
3 years ago
Jaiden's pen pal from Mexico said that he lives 3.3 kilometers from school. Jaiden knows
marissa [1.9K]

Answer:

2 miles

Step-by-step explanation:

3.3 kilometers to miles is 2.0505. I'm not sure if this question want you to round, but if it does, the answer would be 2 miles.

To get your approximate answer, multiply 3.3 (kilometers) by 0.62 (miles).

You get 2.046 if you multiply it by 0.62 like the question says to do.

3 0
3 years ago
Read 2 more answers
How do i solve x/3+10=15
yaroslaw [1]

step-by-step.

x

3

+10=15

Step 1: Simplify both sides of the equation.

1

3

x+10=15

Step 2: Subtract 10 from both sides.

1

3

x+10−10=15−10

1

3

x=5

Step 3: Multiply both sides by 3.

3*(

1

3

x)=(3)*(5)

x=15

Answer:

x=15

8 0
3 years ago
The seventh term of an arithmetic progression is equal to twice the fifth term. The sum
mario62 [17]

Answer:

a₁ = - 24

Step-by-step explanation:

The n th term of an AP is

a_{n} = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Given a₇ = 2a₅ , then

a₁ + 6d = 2(a₁ + 4d) = 2a₁ + 8d ( subtract 2a₁ + 8d from both sides )

- a₁ - 2d = 0 → (1)

The sum to n terms of an AP is

S_{n} = \frac{n}{2} [ 2a₁ + (n - 1)d ]

Given S_{7} = 84 , then

\frac{7}{2} (2a₁ + 6d) = 84

3.5(2a₁ + 6d) = 84 ( divide both sides by 3.5 )

2a₁ + 6d = 24 → (2)

Thus we have 2 equations

- a₁ - 2d = 0 → (1)

2a₁ + 6d = 24 → (2)

Multiplying (1) by 3 and adding to (2) will eliminate d

- 3a₁ - 6d = 0 → (3)

Add (2) and (3) term by term to eliminate d

- a₁ = 24 ( multiply both sides by - 1 )

a₁ = - 24

6 0
3 years ago
What are all the angles?
mrs_skeptik [129]

Answer:

Step-by-step explanation:

So you should know. Can you give us a better picture?

5 0
2 years ago
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