For each race, there are only two possible outcomes. Either the person has a crash, or the person does not. The probability of having a crash during a race is independent of whether there was a crash in any other race. This means that the binomial probability distribution is used to solve this question.

Binomial probability distribution

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

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

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

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

And p is the probability of X happening.

A certain performer has an independent .04 probability of a crash in each race.

This means that $p = 0.04$

a) What is the probability she will have her first crash within the first 30 races she runs this season

This is:

$P(X \geq 1) = 1 - P(X = 0)$

When $n = 30$

We have that:

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

$P(X = 0) = C_{30,0}.(0.04)^{0}.(0.96)^{30} = 0.2939$

$P(X \geq 1) = 1 - P(X = 0) = 1 - 0.2939 = 0.7061$

0.7061 = 70.61% probability she will have her first crash within the first 30 races she runs this season

7 0

3 years ago

Gerry's electric toothbrush rotates the brush 125 times per second.

makkiz [27]

Answer:

Her electric toothbrush makes 210,000 rotations in one week

Step-by-step explanation:

Note that:

1 minute = 60 seconds

1 week= 7 days

∵ Gerry brushes her teeth for two minutes, twice a day

→ Twice means times 2

∴ Gerry brushes her teeth for 2 × 2 = 4 minutes a day

∵ Gerry's electric toothbrush rotates the brush 125 times per second

∵ 1 minute = 60 seconds

→ Multiply 125 by 60 to find the number of rotating in 1 minute

∴ Gerry's electric toothbrush rotates 125 × 60 = 7,500 in 1 minute

∵ Gerry brushes her teeth for 4 minutes a day

→ Multiply it by 4 to find the number of rotation in 1 day

∴ Gerry's electric toothbrush rotates 7,500 × 4 = 30,000 in 1 day

∵ 1 week = 7 days

→ Multiply the number of rotation in 1 day by 7 to find it in 1 week

∴ Gerry's electric toothbrush rotates 30,000 × 7 = 210,000 in 1 week

∴ Her electric toothbrush makes 210,000 rotations in one week

3 0

3 years ago

Express the function graphed on the axes below as a piecewise function.

dangina [55]

Answer:

y = 2/3x +6 for x< -3

y = 2/3x +1 for x> 3

Step-by-step explanation:

The graph is a line for x < -3

( - 6,2) and ( -3,4)

The slope is m= ( y2-y1)/(x2-x1)

m = ( 4-2)/(-3 - -6) = 2/ ( -3+6) = 2/3

The slope is 2/3

Using point slope form

y-y1 = m(x-x1) and the point ( -6,2)

y -2 = 2/3(x - -6)

y -2 = 2/3(x +6)

y-2 = 2/3 x +4

y = 2/3x +6 x< -3

The graph is a line for x > 3

(3,3) and ( 6,5)

The slope is m= ( y2-y1)/(x2-x1)

m = ( 5-3)/(6-3) = 2/ (3) = 2/3

The slope is 2/3

Using point slope form

y-y1 = m(x-x1) and the point (6,5)

y -5 = 2/3(x - 6)

y-5 = 2/3 x -4

y = 2/3x +1 x> 3

8 0

3 years ago