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Bunuel
The amount of electrical current that flows through a wire is inversely proportional to the resistance in that wire. If a wire currently carries 4 amperes of electrical current, but the resistance is then cut to one-third of its original value, how many of electrical current will flow through the wire?

A. 3/4 amperes
B. 4/3 amperes
C. 4 amperes
D. 8 amperes
E. 12 amperes

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Current flow = 4 ampere = 1/4 resistance
New Flow = 12 ampere = 1/12 resistance*

New resistance = 1/3 * 1/4 = 1/12

Answer E.
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Bunuel
The amount of electrical current that flows through a wire is inversely proportional to the resistance in that wire. If a wire currently carries 4 amperes of electrical current, but the resistance is then cut to one-third of its original value, how many of electrical current will flow through the wire?

A. 3/4 amperes
B. 4/3 amperes
C. 4 amperes
D. 8 amperes
E. 12 amperes

Kudos for a correct solution.

Directly Proportional : The relation when due to increase in one variable, other variable needs to be increased is called a Directly Proportional Relationship e.g. Speed and Distance. "More Distance in same time require more speed and Vise versa"

Inversely Proportional : The relation when due to increase in one variable, other Variable needs to be Decreased is called a Inversely Proportional Relationship e.g. Speed and Time. "More Speed will cover a specific Distance in Less time and Vise versa"



Given: Current is INVERSELY Proportional to Resistance

i.e. Current = (1/Resistance)*Constant [Removal of Proportional sign always comes with a constant]

i.e. \(Current_1 / Current_2 = Resistance_2 / Resistance_1\)

If Initially Resistance = \(R_1\)
Then, \(R_2 = (1/3)*R_1\)
Current after reducing Resistance, \(C_2 = ?\)
Current Before reducing Resistance, \(C_1 = 4\)

\(4 / C_2 = (1/3)*R_1 / R_1\)

i.e. \(C_2 = 4*3 = 12\) Amperes

Answer: Option
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Bunuel
The amount of electrical current that flows through a wire is inversely proportional to the resistance in that wire. If a wire currently carries 4 amperes of electrical current, but the resistance is then cut to one-third of its original value, how many of electrical current will flow through the wire?

A. 3/4 amperes
B. 4/3 amperes
C. 4 amperes
D. 8 amperes
E. 12 amperes

Kudos for a correct solution.

Current * resistance = K constant.

If resistance is dropped to 1/3rd then current must be tripled to maintain the product constant.

Hence Option E is correct.
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Bunuel
The amount of electrical current that flows through a wire is inversely proportional to the resistance in that wire. If a wire currently carries 4 amperes of electrical current, but the resistance is then cut to one-third of its original value, how many of electrical current will flow through the wire?

A. 3/4 amperes
B. 4/3 amperes
C. 4 amperes
D. 8 amperes
E. 12 amperes

Kudos for a correct solution.

MANHATTAN GMAT OFFICIAL SOLUTION:

While you are not given precise amounts for the “before” or “after” resistance in the wire, you can pick numbers. Using 3 as the original resistance and 1 as the new resistance, you can see that the new electrical current will be 12 amperes:

\(C_1R_1=C_2R_2\);

\(4*3=C_2*1\);

\(C_2=12\).

Answer: E.
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4 = 1/R or R = 1/4
if resistance is cut to 1/3 of what it was, then the new resistance is 1/4 * 1/3 or 1/12

since we know that the amount of electrical current is indirectly proportional to resistance, then 1 : 1/12 = 12. Thus, E is the answer.
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Voltage = Current * Resistance
Resistance drops to 1/3 of original value, therefore current will increase by 3 times.
4 * 3 = 12 A
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\(c=\frac{k}{r}\)
\(4=\frac{k}{r}\)
\(k=4r\)

After cutting resistance

\(c=\frac{k}{\frac{r}{3}}\)
\(c=\frac{3k}{r}\)
\(c=\frac{3*4r}{r}\)
\(c=12\)
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Bunuel
The amount of electrical current that flows through a wire is inversely proportional to the resistance in that wire. If a wire currently carries 4 amperes of electrical current, but the resistance is then cut to one-third of its original value, how many of electrical current will flow through the wire?

A. 3/4 amperes
B. 4/3 amperes
C. 4 amperes
D. 8 amperes
E. 12 amperes

Kudos for a correct solution.

For a conceptual discussion of inverse variation, check this link: https://youtu.be/AT86tjxJ-f0
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