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3 years ago

Please help me with this. I'm stuck

Mathematics

2 answers:

Anon25 [30]3 years ago

8 0

Answer:

Step-by-step explanation:

7 choose 2 or

=7! / (7-2)!

=7*6*5*4*3*2*1 / 5*4*3*2*1

=7*6

=42

MatroZZZ [7]3 years ago

5 0

Answer:

It is 42!

Step-by-step explanation:

Your welcome! :)

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Negative Exponents- All of the following expressions are equal except _____.

UNO [17]

7 is not equal to the others

using the laws of exponents

$7^{2}$ / $7^{3}$ = 1 / $7^{3-2}$ = $\frac{1}{7}$

$7^{-1}$ = $\frac{1}{7}$

Apart from 7 the other 3 all equal $\frac{1}{7}$

4 0

3 years ago

Hans needs to rent a moving truck. suppose company a charges a rate of $40 per day and company B charges $60 fee plus $30 per da

kykrilka [37]

The time at which the cost for the services of the two companies would be in exactly 6 days. If we would compare the two charges, we would see that company A just charges 40 per day while B has a charge of 60, which is a standard fee, and a rate of 30 per day. So if we compute 40 x 6, we will have a total cost now of 240. If we compute 30 x 6, we will have a total cost now of 180 plus 60 which is the standard fee, and we will get 240. So in 6 days, the rates of the two companies would both accumulate to 240.

8 0

3 years ago

Can I have some help

TiliK225 [7]

What do you need help with

8 0

3 years ago

What is 9 superscript 7 written in expanded form? 9 + 9 + 9 + 9 + 9 + 9 + 9 9 times 9 times 9 times 9 times 9 times 9 times 9 7

GrogVix [38]

Answer:

4,782,969

Step-by-step explanation:

9^7

Written in expanded form = 9 times 9 times 9 times 9 times 9 times 9 times 9

= 9 × 9 × 9 × 9 × 9 × 9 × 9

= 4,782,969

9^7 means multiplying 9 in 7 places

9^7 = 4,782,969

3 0

2 years ago

Read 2 more answers

When circuit boards used in the manufacture of compact disc players are tested, the long-run percentage of defectives is 5%. Let

sergiy2304 [10]

Answer:

(a) P(X=3) = 0.093

(b) P(X≤3) = 0.966

(c) P(X≥4) = 0.034

(d) P(1≤X≤3) = 0.688

(e) The probability that none of the 25 boards is defective is 0.277.

(f) The expected value and standard deviation of X is 1.25 and 1.089 respectively.

Step-by-step explanation:

We are given that when circuit boards used in the manufacture of compact disc players are tested, the long-run percentage of defectives is 5%.

Let X = the number of defective boards in a random sample of size, n = 25

So, X ∼ Bin(25,0.05)

The probability distribution for the binomial distribution is given by;

$P(X=r)= \binom{n}{r} \times p^{r}\times (1-p)^{n-r} ; x = 0,1,2,......$

where, n = number of trials (samples) taken = 25

r = number of success

p = probability of success which in our question is percentage

of defectivs, i.e. 5%

(a) P(X = 3) = $\binom{25}{3} \times 0.05^{3}\times (1-0.05)^{25-3}$

= $2300 \times 0.05^{3}\times 0.95^{22}$

= 0.093

(b) P(X $\leq$ 3) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3)

= $\binom{25}{0} \times 0.05^{0}\times (1-0.05)^{25-0}+\binom{25}{1} \times 0.05^{1}\times (1-0.05)^{25-1}+\binom{25}{2} \times 0.05^{2}\times (1-0.05)^{25-2}+\binom{25}{3} \times 0.05^{3}\times (1-0.05)^{25-3}$

= $1 \times 1 \times 0.95^{25}+25 \times 0.05^{1}\times 0.95^{24}+300 \times 0.05^{2}\times 0.95^{23}+2300 \times 0.05^{3}\times 0.95^{22}$

= 0.966

(c) P(X $\geq$ 4) = 1 - P(X < 4) = 1 - P(X $\leq$ 3)

= 1 - 0.966

= 0.034

(d) P(1 ≤ X ≤ 3) = P(X = 1) + P(X = 2) + P(X = 3)

= $\binom{25}{1} \times 0.05^{1}\times (1-0.05)^{25-1}+\binom{25}{2} \times 0.05^{2}\times (1-0.05)^{25-2}+\binom{25}{3} \times 0.05^{3}\times (1-0.05)^{25-3}$