Seeking a job

A blonde walks into the police department looking for a job. The officer wants to ask her a few questions...

Officer: What's 2+2? Blonde: "Ummmmm... 4!"

Officer: "What's the square root of 100?" Blonde: "Ummmm... 10!"

Officer: "Good! Now, who killed Abraham Lincoln?" Blonde: "Ummmm... I dunno". Officer: "Well, you can go home and think about it. Come back tomorrow".

The blonde goes home and calls up one of her friends, who asks her if she got the job. The blonde says, excitedly

Spoiler:

"Not only did I get the job, I'm already working on a murder case!"