One-tenth of the students at a nursery school are 4 years old or older. If 20 students have not yet reached their third birthday, and a total of 50 students are not between 3 years old and 4 years old, how many children are in the nursery school?	Pick one:  A) 150  B) 300  C) 450  D) 490  E) 620
x/10 students are &gt; 4 yrs   20 students are &lt; 3 yrs   x/10+ 20 = 50   x/10 = 30   x = 300   Answer: 300
<result>B</result>
One-tenth of the students at a nursery school are 4 years old or older. If 20 students have not yet reached their third birthday, and a total of 50 students are not between 3 years old and 4 years old, how many children are in the nursery school?