What would be a good 4-hour development task for a job interview?

Is this a good cover letter? I'm trying to get a job at future shop or best buy!Suggestions?

• In today’s highly competitive and fast-paces market, organizations need strong and aggressive sales leadership to meet ever-changing business development goals. I am certain I can contribute this level of performance to your team, and I invite you to consider my qualifications and accomplishments. I believe my educational background and work experience duly qualifies me for this position within your team. Currently I am a full-time student enrolled at Merivale High School. I have successfully completed three years and going on my last and fourth year. Presently, I have maintained an 80% average in school, and hoping to keep it that way. In, University I’m looking to enroll in the political science and law programs. As my resume also will demonstrate in great detail, I have many skills that I can bring to this position through my previous work experience. Through my previous sales and retail positions, I have developed strong communication, customer service, and sales skills, as well as learned to be a team player, which I know is very important. I bring a strong work ethic and genuine eagerness to every task I approach. I am available for an interview anytime to discuss my suitability to work as a marine engineering cadet. I look forward to hearing from you soon and can be reached at (613)822-2642. Thank you for your time and consideration. Sincerely,

• Answer:

  I sincerely hope that's not a real telephone number you've just posted. You should have the business address and your address on your cover letter but phone numbers should be left to your resumé or CV. You need to watch your commas. You have too many. You also need to watch your words. Are you using the right ending? Say, do you need a "d" rather than an "s" on a word? You also need to make sure that Future Shop or Best Buy needs a marine engineering cadet. It's a start but you do have some errors that need correcting. These errors could cost you and interview.