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3 years ago

5

In a survey of 100 people, some of them jog for exercise, some of them ride a bike, some do both, and 15 do not jog or ride a bi

ke. If 46 of the people surveyed job and 21 of them both jog and ride a bike, how many of the people surveyed only ride a bike?

1 answer:

masya89 [10]3 years ago

8 0

Answer:

Bike alone = 39

Step-by-step explanation:

Given that:

Total number = n(T) = 100

Jog= n(J)

Bike = n(B)

Bike and jog = n(BnJ) = 21

Number who jog = 46

Jog alone = 46 - 21 = 25

Neither jog nor bike = 15

Let bike alone = x

Hence,

Jog alone + bike alone + jog and bike + none of the two = 100

25 + x + 21 + 15 = 100

x = 39

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Andrew drove 45 more miles than Nicole. If they drove a combined total of 111 miles, how many miles did Nicole drive?

Airida [17]

Answer:

Nicole drove 66 miles.

Step-by-step explanation:

You can set of an equation of 45 - x = 111 x representing the amount of miles Nicole drove. You would subtract 45 from both 45 and 111 and get that x = 66.

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3 years ago

Solve this proportion 9/v = 3/2 a. {6} b. {7.3} c. {4.4} d. {1.3} What percent of 151 is 119.5? a. 129.8% b. 126.4% c. 79.1% d.

Roman55 [17]

V = ( 9*2 ) / 3 ;
v = 18 / 3 ;
v = 6 ;
a. is the right answer;

( 119.5 / 151 ) * 100 = 11950 / 151 = 79.1 ;

The percent is 79.1%;

c. is the right answer;

1 - (40/100)*1 = 1 - 2 / 5 = 3 / 5 = 0.60 ;
d. is the right answer.

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3 years ago

Two teams of movers are lowering a piano from the window of a 10 floor apartment building. The rope breaks when the piano is 30

GuDViN [60]

By solving the motion equations for the piano, we will see that they have 0.7 seconds to react.

<h3>How to find the motion equation for the piano.</h3>

So the piano is in a free fall from a height of 30m.

The motion equations will be given by:

The only force acting on the piano will be the gravitational one, thus the acceleration of the piano is the gravitational acceleration: a(t) = -9.8m/s^2 (Where the negative sign is because it is falling down).
To get the velocity we integrate over time, because the piano has no initial velocity, the constant of integration is zero: v(t) = (-9.8m/s^2)*t
To get the position equation we integrate again, here the initial position is 30 meters above the ground, so that will be our constant of integration: p(t) = (1/2)*(-9.8m/s^2)*t^2 + 30m

<h3>How long takes to fall?</h3>

We want to find the value of t such that the position is equal to zero, so we need to solve:

0 = (1/2)*(-9.8m/s^2)*t^2 + 30m

30m = (1/2)*(9.8m/s^2)*t^2

2*30m/(9.8m/s^2) = t^2

6.1 s^2 = t^2

√(6.1 s^2) = 2.5s = t

This means that the piano falls to the ground in 2.5 seconds.

But the workes notice it when the piano is 14 meters above the ground, it happens when:

p(t) = 14m = (1/2)*(-9.8m/s^2)*t^2 + 30m

Solving that we get:

30m - 14m = (1/2)*(9.8m/s^2)*t^2

2*16m/(9.8m/s^2) = t^2

3.27s^2 = t^2

√(3.27s^2) = t = 1.8s

So the piano falls in 2.5 seconds, and the works notice it 1.8 seconds after it starts falling, meaning that they have:

2.5 - 1.8 = 0.7 seconds to react.

If you want to learn more about motion equations, you can read:

brainly.com/question/2473092

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2 years ago

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.2.a. If the distri

zalisa [80]

Answer:

a

$P(\= X \ge 51 ) =0.0062$

b

$P(\= X \ge 51 ) = 0$

Step-by-step explanation:

From the question we are told that

The mean value is $\mu = 50$

The standard deviation is $\sigma = 1.2$

Considering question a

The sample size is n = 9

Generally the standard error of the mean is mathematically represented as

$\sigma_x = \frac{\sigma }{\sqrt{n} }$

=> $\sigma_x = \frac{ 1.2 }{\sqrt{9} }$

=> $\sigma_x = 0.4$

Generally the probability that the sample mean hardness for a random sample of 9 pins is at least 51 is mathematically represented as

$P(\= X \ge 51 ) = P( \frac{\= X - \mu }{\sigma_{x}} \ge \frac{51 - 50 }{0.4 } )$

$\frac{\= X -\mu}{\sigma } = Z (The \ standardized \ value\ of \ \= X )$

$P(\= X \ge 51 ) = P( Z \ge 2.5 )$

=> $P(\= X \ge 51 ) =1- P( Z < 2.5 )$

From the z table the area under the normal curve to the left corresponding to 2.5 is

$P( Z < 2.5 ) = 0.99379$

=> $P(\= X \ge 51 ) =1-0.99379$

=> $P(\= X \ge 51 ) =0.0062$

Considering question b

The sample size is n = 40

Generally the standard error of the mean is mathematically represented as

$\sigma_x = \frac{\sigma }{\sqrt{n} }$

=> $\sigma_x = \frac{ 1.2 }{\sqrt{40} }$

=> $\sigma_x = 0.1897$

Generally the (approximate) probability that the sample mean hardness for a random sample of 40 pins is at least 51 is mathematically represented as

$P(\= X \ge 51 ) = P( \frac{\= X - \mu }{\sigma_x} \ge \frac{51 - 50 }{0.1897 } )$

=> $P(\= X \ge 51 ) = P(Z \ge 5.2715 )$

=> $P(\= X \ge 51 ) = 1- P(Z < 5.2715 )$

From the z table the area under the normal curve to the left corresponding to 5.2715 and

=> $P(Z < 5.2715 ) = 1$

So

$P(\= X \ge 51 ) = 1- 1$

=> $P(\= X \ge 51 ) = 0$

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3 years ago

Donnavan is measuring the angles of a triangle. He measures the first two angles and gets 10° and 120°. What should be the measu

stepladder [879]

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3 years ago

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