Melissa has a choice of two phone plans.

The rates of on-time flights for commercial jets are continuously tracked by the U.S. Department of Transportation. Recently, So

tatyana61 [14]

Answer:

The probability that at least 13 flights arrive late is 2.5196 $\times 10^{-6}$ .

Step-by-step explanation:

We are given that Southwest Air had the best rate with 80 % of its flights arriving on time.

A test is conducted by randomly selecting 18 Southwest flights and observing whether they arrive on time.

The above situation can be represented through binomial distribution;

$P(X = x) = \binom{n}{r}\times p^{r} \times (1-p)^{n-r} ; x = 0,1,2,3,.........$

where, n = number of trials (samples) taken = 18 Southwest flights

r = number of success = at least 13 flights arrive late

p = probability of success which in our question is probability that

flights arrive late, i.e. p = 1 - 0.80 = 20%

Let X = <u><em>Number of flights that arrive late</em></u>.

So, X ~ Binom(n = 18, p = 0.20)

Now, the probability that at least 13 flights arrive late is given by = P(X $\geq$ 13)

P(X $\geq$ 13) = P(X = 13) + P(X = 14) + P(X = 15) + P(X = 16) + P(X = 17) + P(X = 18)

= $\binom{18}{13}\times 0.20^{13} \times (1-0.20)^{18-13}+ \binom{18}{14}\times 0.20^{14} \times (1-0.20)^{18-14}+ \binom{18}{15}\times 0.20^{15} \times (1-0.20)^{18-15}+ \binom{18}{16}\times 0.20^{16} \times (1-0.20)^{18-16}+ \binom{18}{17}\times 0.20^{17} \times (1-0.20)^{18-17}+ \binom{18}{18}\times 0.20^{18} \times (1-0.20)^{18-18}$

= $\binom{18}{13}\times 0.20^{13} \times 0.80^{5}+ \binom{18}{14}\times 0.20^{14} \times 0.80^{4}+ \binom{18}{15}\times 0.20^{15} \times 0.80^{3}+ \binom{18}{16}\times 0.20^{16} \times 0.80^{2}+ \binom{18}{17}\times 0.20^{17} \times 0.80^{1}+ \binom{18}{18}\times 0.20^{18} \times 0.80^{0}$

= 2.5196 $\times 10^{-6}$ .

7 0

3 years ago

Help me with my math**30 pts** i mark brainiest**

xxMikexx [17]

Answer:

3.vertically opposite angle

4.side of a congruent triangle are equal

5 0

2 years ago

In two or more complete sentences, compare the number of x-intercepts in the graph of f(t) = t2 to the number of x-intercepts in

Strike441 [17]

F rests at (0/0) and grows upwards, so there is only a single x-intercept. g is f moved 3 to the left, so it also only has one intercept but at (-3,0).

6 0

3 years ago

Read 2 more answers

Please help I know that B is wrong because I just took it and it was wrong

svlad2 [7]

If he flipped the coin 100 times and got 50 heads, then the answer would be 0.5 (since 50/100 = 1/2 = 0.5). I think you might be mixing theoretical probability with empirical probability.

In this case, he got 28 heads out of 75 flips
so 28/75 = 0.373333... where the 3's repeat forever
This rounds to 0.37

That's why the answer is actually choice A

7 0

3 years ago

Read 2 more answers

Solve for the base. Round to hundredths when necessary.

Elena-2011 [213]

Answer:

2730.54
18.8%
62.5% (decrease)

Step-by-step explanation:

The applicable formula is ...

rate = portion/base

so ...

base = portion/rate

Of course, a percentage is a fraction that has been multiplied by 100%.

__

1. base = portion/rate = 456/0.167 ≈ 2730.54

The base is about 2730.54.

__

2. rate = portion/base = 50/266 ≈ 0.18797 ≈ 18.8%

The rate is about 18.8%.

__

3. The decrease can be figured from ...

rate of change = (new amount)/(original) -1 = 33/88 -1

= -5/8 = -0.625 = -62.5%

The rate of decrease is 62.5%.

6 0

3 years ago