Sometimes seemingly simply questions will have a hidden agenda, but more often than not, the interviewer is trying to gauge your true interest in the company and what value you can bring to its work force.
If asked, "Why do you want to work here?" that's a perfect opportunity to show the company you've done your homework. The interviewer wants details -- how does this company stand apart from its competitors, what new products or services are they offering -- and this is the moment to shine by having well-researched answers ready to deliver. If possible, mention something you are particularly familiar with about the company that you can link directly to your own work experience and talents.
Even when asked the inevitable "What are your strengths?" find something in your own background that shows the particular talents you bring to this company's table. Put your strongest qualities into the context of what this prospective employer does and how they meet the company's goals.
Then there's the flip side: "What are your weaknesses?" For years, people have been counseled to envelope their "weakness" in an answer that actually makes it sound like a strength. But job interviewers have heard them all, and those answers tend to sound hollow these days. Rather, choose a time when you had to face a significant challenge or adversity -- without getting too personal -- and tell how you overcame that dilemma and were improved by it. Tell what you learned and how that newfound knowledge benefited you as a professional. People who recognize their weaknesses and show they want to do better are showing a prospective employer they are willing to do their best, even if it means learning from mistakes.
The company wants a team player and an independent worker
When you are asked whether you work better alone or in a team, what they really want to know is how you interact with others and how much direction you need when you're assigned to work by yourself.
If you use time alone well, are you able to keep your boss posted on your progress at reasonable intervals? Are you good at brainstorming in a group, the one who comes up with rapid-fire ideas? Or are you the person who is likely to mold them into a collaborative effort to find a solution for the challenge at hand? Either alone or in a team, you want to convey that you can interact well with co-workers at various levels of authority, but that you're a person who can be productive and come up with answers on your own as well.
Remember, an interview is a two-way street, and that's true where questions are concerned. Be sure to ask questions that show you have researched the company and that you're aware of current issues faced by the company and the industry it's in. You need to show an interest in the company if you want it to show an interest in you.