A group of 4th graders and 5th graders is going on a field trip to the zoo. Only 20% of the students remembered to bring written permission from their parents. If 40% of the students are 4th graders and 25% if the 4th graders remembered to bring written permission, what percentage of the students are 5th graders who forgot to bring written permission? Choose the correct choice from the following answers
A) 10%  B) 30%  C) 50%  D) 60%  E) 80%
Assume that the total number of students is 100.   =&gt; 20 students got permission from their parents, 40 students are 4th graders, and 10 of the 4th graders got permission from their parents   =&gt; 30 of the 5th graders got written permission   =&gt; 30 of the 5th graders did not get written permission (there are 60 students who are 5th graders)   =&gt; 50% of the 5th graders didn't get permission   Option (50%)
<result>C</result>
A group of 4th graders and 5th graders is going on a field trip to the zoo. Only 20% of the students remembered to bring written permission from their parents. If 40% of the students are 4th graders and 25% if the 4th graders remembered to bring written permission, what percentage of the students are 5th graders who forgot to bring written permission?