The Siemens competition was first held in 1998 and is distinct from the Westinghouse Science Talent Search, which was founded in 1941 and is now known as the Intel Science Talent Search. Many high school students enter both.

Image Janelle Schlossberger, left, and Amanda Marinoff, students at a Long Island high school, were announced as the winners in the team category. They will split a $100,000 scholarship. Credit... Ruby Washington/The New York Times

This year, more than 1,600 students nationwide entered the Siemens competition. After several rounds of judging, 20 finalists were chosen to present their projects at N.Y.U. and to vie for scholarships ranging from $10,000 to $100,000. Eleven of the finalists were girls. It was the first year that girls outnumbered boys in the final round. Most of the finalists attend public school.

On Sunday, the students gave 12-minute presentations of their projects, filled with explanations about Herceptin resistance (when breast cancer patients with HER2-positive tumors do not respond to the drug Herceptin) and FtsZ inhibitors (experiments on a specific protein that could lead to a new treatment for drug-resistant tuberculosis).

One of the most popular was by three home-schooled girls from Pennsylvania and New Jersey — Caroline Lang, 16; Rebecca Ehrhardt, 15; and Naomi Collipp, 16 — who used a Power Point presentation to demonstrate their “Burgercam” monitoring system. It is designed to determine when E. coli bacteria in hamburgers have been safely eliminated by measuring the shrinkage of each patty when fully cooked.

Several hundreds of hamburgers later, the girls took home fifth place and $20,000 in scholarship money.

Caroline, Rebecca and Naomi, called “the Hamburger Girls,” said they had been friends since they were toddlers and had stayed in touch through a group for home-schooled children.

“They were concerned it wasn’t sophisticated enough, but they wanted to try,” said Rebecca’s mother, Alicia Butcher Ehrhardt, a plasma physicist.