Algebra II : Algebra II

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #6 : Indirect Proportionality

The number of hours needed for a contractor to finish a job varies indirectly with the total number of people the contractor hires. If the job is completed in  hours when there are  people, how many hours would it take if there were  people?

Possible Answers:

Correct answer:

Explanation:

The problem follows the formula 

 

where H is the number of hours to complete the job, n is the number of people hired, and k is the constant of variation.

Setting H=6 and n = 8 yields k=48.

Therefore using the following equation we can plug 16 in for n and solve for H.

Therefore H is 3 hours.

Example Question #1 : Indirect Proportionality

 varies inversely with . If  ,  . What is the value of  if  ? 

Possible Answers:

Correct answer:

Explanation:

 varies inversely with , so the variation equation can be written as:

 can be solved for, using the first scenario:

Using this value for  = 30 and  = 90, we can solve for :

Example Question #1871 : Algebra Ii

 varies directly with  and inversely with the square root of . Find values for  and  that will give , for a constant of variation .  

Possible Answers:

 and 

All of these answers are correct

 and 

 and 

Correct answer:

All of these answers are correct

Explanation:

From the first sentence, we can write the equation of variation as:

We can then check each of the possible answer choices by substituting the values into the variation equation with the values given for  and .

 

Therefore the equation is true if  and 

 

Therefore the equation is true if  and 

 

Therefore the equation is true if  and 

The correct answer choice is then "All of these answers are correct" 

Example Question #31 : Proportionalities

 varies directly with  and . If  and , then . Find if  and

Possible Answers:

None of these answers are correct

Correct answer:

Explanation:

From the relationship of , , and ; the equation of variation can be written as:

Using the values given in the first scenario, we can solve for k:

Using the value of k and the values of y and z, we can solve for x:

Example Question #1872 : Algebra Ii

 varies inversely with  and the square root of . When  and . Find  when  and .

Possible Answers:

None of these answers are correct

Correct answer:

Explanation:

First, we can create an equation of variation from the the relationships given:

Next, we substitute the values given in the first scenario to solve for :

Using the value for , we can now use the second values for  and  to solve for :

Example Question #1873 : Algebra Ii

 varies directly with  and the square root of . If , and  then . Find the value of  if  and .

Possible Answers:

None of these answers are correct

Correct answer:

Explanation:

From the relationship given, we can set up the variation equation

Using the first relationship, we can then solve for 

Now using the values from the second relationship, we can solve for x

Example Question #1 : How To Find Inverse Variation

 varies inversely as the square of . If , then . Find  if  (nearest tenth, if applicable).

Possible Answers:

Correct answer:

Explanation:

The variation equation is  for some constant of variation .

Substitute the numbers from the first scenario to find :

 

The equation is now .

If , then

Example Question #2 : How To Find Inverse Variation

The current, in amperes, that a battery provides an electrical object is inversely proportional to the resistance, in ohms, of the object.

A battery provides 1.2 amperes of current to a flashlight whose resistance is measured at 20 ohms. How much current will the same battery supply to a flashlight whose resistance is measured at 16 ohms?

Possible Answers:

Correct answer:

Explanation:

If  is the current and  is the resistance, then we can write the variation equation for some constant of variation :

 

or, alternatively, 

To find  , substitute :

The equation is . Now substitute  and solve for :

Example Question #1 : How To Find Direct Variation

The volume of a fixed mass of gas varies inversely as the atmospheric pressure, as measured in millibars, acting on it, and directly as the temperature, as measured in kelvins, acting on it.

A balloon is filled to a capacity of exactly 100 cubic meters at a time at which the temperature is 310 kelvins and the atmospheric pressure is 1,020 millibars. The balloon is released, and an hour later, the balloon is subject to a pressure of 900 millibars and a temperature of 290 kelvins. To the nearest cubic meter, what is the new volume of the balloon?

Possible Answers:

Correct answer:

Explanation:

If  are the volume, pressure, and temperature, then the variation equation will be, for some constant of variation ,

To calculate , substitute :

The variation equation is 

so substitute  and solve for 

Example Question #7 : How To Find Inverse Variation

If  is inversely proportional to  and knowing that  when , determine the proportionality constant.

Possible Answers:

Correct answer:

Explanation:

The general formula for inverse proportionality for this problem is

Given that  when , we can find  by plugging them into the formula.

Solve for  by multiplying both sides by 5

So .

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