The problem says the charge is same as an electron's but positive. Shouldn't the answer also be raised to a positive power (5.5*10^11 A)?

Hi eupaulinha,

Thanks a lot for the question. The answer is correct as shown. Compare 5.5*10^(-11) with -5.5*10^(-11). Both of these answers have a negative exponent for the scientific notation, but the first answer is a "positive number", whereas the second answers is a "negative number" because it's the sign in front of the 5.5 that matters. The negative exponent for 5.5*10^(-11) means the number is really small (55 picoAmps), but still positive.

Hope this helps, and let me know if you have other questions.