An electronic device is a circuit composed of three resistors, of which * * * has six solder joints, ABCDEF. If the solder joint falls off, the circuit will be broken. Now the circuit is different, and the possibility of solder joint falling off is * * *

Solution:

There are six cases of solder joint falling off;

Because there are six solder joints.

And so on: two solder joints fall off in two situations: C (6 6,2) = (6× 5)/(2×1) =15;

There are 20 cases of three solder joints falling off: c (6 6,3) = (6× 5× 4)/(3× 2×1);

When c (6,4) = c (6,2) =15, four solder joints fall off;

There are six cases in which the five solder joints fall off: c(6,5) = c (6, 1)=6 cases;

There is only one case where six solder joints fall off.

Through addition principle.

The possibility of solder joint falling off * * * are:

6+15+20+15+6+1= 63 possibilities.