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rosijanka [135]
3 years ago
9

Kevin and Randy Muise have a jar containing 82 ​coins, all of which are either quarters or nickels. The total value of the coins

in the jar is ​$12.10. How many of each type of coin do they​ have? The jar contains nothing quarters.
Mathematics
1 answer:
mezya [45]3 years ago
7 0

Answer: The jar contains 40 quarters and 42 nickels.

Step-by-step explanation:

The worth of a quarter is 25 cents. Converting to dollars, it becomes

25/100 = $0.25

The worth of a nickel is 5 cents. Converting to dollars, it becomes

5/100 = $0.05

Let x represent the number of quarters that they have in the jar.

Let y represent the number of nickels that they have in the jar.

Kevin and Randy Muise have a jar containing 82 ​coins, all of which are either quarters or nickels. This means that

x + y = 82

The total value of the coins in the jar is ​$12.10. This means that

0.25x + 0.05y = 12.1 - - - - - - - - - - - 1

Substituting x = 82 - y into equation 1, it becomes

0.25(82 - y) + 0.05y = 12.1

20.5 - 0.25y + 0.05y = 12.1

- 0.25y + 0.05y = 12.1 - 20.5

- 0.2y = - 8.4

y = - 8.4/ - 0.2

y = 42

x = 82 - y = 82 - 42

x = 40

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Papessa [141]

Answer:

x = - 1 + \sqrt{17}\\and\\x = - 1 - \sqrt{17}\\

Step-by-step explanation:

given equation

x^2 +2x +1 = 17

subtracting 17 from both sides

x^2 +2x +1 = 17\\x^2 +2x +1 -17= 17-17\\x^2 +2x - 16 = 0\\

the solution for quadratic equation

ax^2 + bx + c = 0 is given by

x = x = -b + \sqrt{b^2 - 4ac} /2a \\\\and \ \\-b - \sqrt{b^2 - 4ac} /2a

________________________________

in our problem

a = 1

b = 2

c = -16

x =( -2 + \sqrt{2^2 - 4*1*-16}) /2*1 \\x =( -2 + \sqrt{4  + 64}) /2\\x =( -2 + \sqrt{68} )/2\\x = ( -2 + \sqrt{4*17} )/2\\x =  ( -2 + 2\sqrt{17} )/2\\x = - 1 + \sqrt{17}\\and\\\\x = - 1 - \sqrt{17}\\

thus value of x is

x = - 1 + \sqrt{17}\\and\\x = - 1 - \sqrt{17}\\

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A public bus company official claims that the mean waiting time for bus number 14 during peak hours is less than 10 minutes. Kar
ch4aika [34]

Answer:

We conclude that the mean waiting time is less than 10 minutes.

Step-by-step explanation:

We are given that a public bus company official claims that the mean waiting time for bus number 14 during peak hours is less than 10 minutes.

Karen took bus number 14 during peak hours on 18 different occasions. Her mean waiting time was 7.8 minutes with a standard deviation of 2.5 minutes.

Let \mu = <u><em>mean waiting time for bus number 14.</em></u>

So, Null Hypothesis, H_0 : \mu \geq 10 minutes      {means that the mean waiting time is more than or equal to 10 minutes}

Alternate Hypothesis, H_A : \mu < 10 minutes    {means that the mean waiting time is less than 10 minutes}

The test statistics that would be used here <u>One-sample t test statistics</u> as we don't know about the population standard deviation;

                       T.S. =  \frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }  ~ t_n_-_1

where, \bar X = sample mean waiting time = 7.8 minutes

             s = sample standard deviation = 2.5 minutes

             n = sample of different occasions = 18

So, <u><em>test statistics</em></u> =  \frac{7.8-10}{\frac{2.5}{\sqrt{18} } }  ~ t_1_7

                              =  -3.734

The value of t test statistics is -3.734.

Now, at 0.01 significance level the t table gives critical value of -2.567 for left-tailed test.

Since our test statistic is less than the critical value of t as -3.734 < -2.567, so we have sufficient evidence to reject our null hypothesis as it will fall in the rejection region due to which <u>we reject our null hypothesis</u>.

Therefore, we conclude that the mean waiting time is less than 10 minutes.

5 0
3 years ago
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