Question

On the last day of school, Mrs. Awesome gave jelly beans to her class. She gave each boy as many jelly beans as there were boys in the class. She gave each girl as many jelly beans as there were girls in the class. She brought $400$ jelly beans, and when she finished, she had six jelly beans left. There were two more boys than girls in her class. How many students were in her class?

Answer 1

Answer:

28 students

Step-by-step explanation:

Let x be the number of girls in the class. There were two more boys than girls in her class, then the number of boys is x + 2.

Mrs. Awesome gave each boy as many jelly beans as there were boys in the class, so each of x + 2 boys got x + 2 jelly beans, so

Number of boys = x + 2

Number of jelly beans each boy got = x + 2

Total number of jelly beans all boys got = (x + 2)(x + 2)

Mrs. Awesome gave each girl as many jelly beans as there were girls in the class, so each of x girls got x jelly beans, so

Number of girls = x

Number of jelly beans each girl got = x

Total number of jelly beans all girls got = (x)(x)

Hence,

Total number of jelly beans class got = (x + 2)(x + 2) + (x)(x)

Mrs. Awesome brought 400 jelly beans, and when she finished, she had six jelly beans left, so she gave 400 - 6 = 394 jelly beans to the calss.

So,

$(x+2)(x+2)+(x)(x)=394\\ \\x^2+2x+2x+4+x^2=394\\ \\2x^2+4x+4-394=0\\ \\2x^2+4x-390=0\\ \\x^2+2x-195=0\\ \\D=2^2-4\cdot (-195)=4+780=784\\ \\\sqrt{D}=28\\ \\x_{1,2}=\dfrac{-2\pm 28}{2\cdot 1}=-15,\ 13$

Number of girls cannot be negative, so x = 13, x + 2 = 15 and total number of students is 13 + 15 = 28