math
posted by n on .
In an electrical circuit, the current passing through a conductor varies inversely with the resistance. Suppose that when the current is 2A (amperes), the resistance is 115ohms. What is the resistance when the current is 5A ?

varies inversely means there is a constant k such that
ir = k
we are told that i=2 when r=115:
2*115 = 230 = k
so, when i=5,
5r = 230
r = 46 ohms