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3 years ago

HELP ASAP PLZ

Mathematics

2 answers:

blagie [28]3 years ago

4 0

9/38 x 9 /38 =81/144 both of the events are indepent

Alisiya [41]3 years ago

4 0

Answer:

The correct option is D. 9/38x9/38 =81/1444

Step-by-step explanation:

Total number of marbles in the bag = 38

Number of white marbles in the bag = 14

Number of gray marbles in the bag = 9

Number of blue marbles in the bag = 15

We need to find the probability that Jane takes out a gray marble in both draws

$\text{Probability that Jane draws gray marble in first draw = }\frac{9}{38}$

Given that : Then Jane replaces the marble for the second draw

$\text{Probability that Jane draws gray marble in second draw = }\frac{9}{38}$

$\text{Probability that Jane draws gray marble in both draws = }\frac{9}{38}\times \frac{9}{38}$

$\text{Probability that Jane draws gray marble in both draws = }\frac{81}{1444}$

Therefore, The correct option is D. 9/38x9/38 =81/1444

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4 years ago

Leon is building a square picture frame. The side of the frame is 345 mm long. If a meter of wood cost seven dollars how much wi

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4 years ago

The playing time X of jazz CDs has the normal distribution with mean 52 and standard deviation 7; N(52, 7).

natita [175]

Answer:

68% of jazz CDs play between 45 and 59 minutes.

Step-by-step explanation:

<u>The correct question is:</u> The playing time X of jazz CDs has the normal distribution with mean 52 and standard deviation 7; N(52, 7).

According to the 68-95-99.7 rule, what percentage of jazz CDs play between 45 and 59 minutes?

Let X = <u>playing time of jazz CDs</u>

SO, X ~ Normal( $\mu=52, \sigma^{2} =7$ )

The z-score probability distribution for the normal distribution is given by;

Z = $\frac{X-\mu}{\sigma}$ ~ N(0,1)

Now, according to the 68-95-99.7 rule, it is stated that;

68% of the data values lie within one standard deviation points from the mean.

95% of the data values lie within two standard deviation points from the mean.

99.7% of the data values lie within three standard deviation points from the mean.

Here, we have to find the percentage of jazz CDs play between 45 and 59 minutes;

For 45 minutes, z-score is = $\frac{45-52}{7}$ = -1

For 59 minutes, z-score is = $\frac{59-52}{7}$ = 1

This means that our data values lie within 1 standard deviation points, so it is stated that 68% of jazz CDs play between 45 and 59 minutes.

6 0

3 years ago

Sarah kicked a ball in the air. The function

Aleksandr-060686 [28]

Answer: The ball hits the ground at 5 s

Step-by-step explanation:

The question seems incomplete and there is not enough data. However, we can work with the following function to understand this problem:

$f=30 t- 6t^{2}$ (1)

Where $f$ models the height of the ball in meters and $t$ the time.

Now, let's find the time $t$ when the ball Sara kicked hits the ground (this is when $f=0 m$ ):

$0=30 t- 6t^{2}$ (2)

Rearranging the equation:

$6t^{2}-30 t=0$ (3)

Dividing both sides of the equation by $6$ :

$t^{2}-5 t=0$ (4)

This quadratic equation can be written in the form $at^{2}+bt+c=0$ , and can be solved with the following formula:

$t=\frac{-b \pm \sqrt{b^{2}-4ac}}{2a}$ (5)

Where:

$a=1$

$b=-5$

$c=0$

Substituting the known values:

$t=\frac{-(-5) \pm \sqrt{(-5)^{2}-4(1)(0)}}{2(1)}$ (6)

Solving we have the following result:

$t=5 s$ This means the ball hit the ground 5 seconds after it was kicked by Sara.

6 0

3 years ago