if i am 11 how old will i be when the life that is leaving the star arcturus reach the earth and how far in kilometers will it have traveled

I am assuming you mean "light" not "life", as I would need more information in order to solve the latter. Wikipedia tells us that Arcturus is 36.7 ± 0.3 lightyears away from the earth, so you will be close to 37 + 11, or 48 years old when the light leaving Arcturus right now reaches you. Light travels 300000 km per second, so you need to calculate the number of seconds in a year: 60sec/min * 60min/hour * 24hour/day * 365 (roughly) days/year = 31536000 seconds. Multiply by 300000 km/sec and you get 9486720000000, which to 3 digits precision is 9.49 * 10 to the 12th kilometers. Multiply that times 36.7 and you get about 347 trillion kilometers. Double-check my work! I might have made a mistake.