Help please!

One hundred students are shown an eight-digit number on a piece of cardboard for three seconds and are asked to then recite the number from memory. The process is repeated until the student accurately recites the entire number from memory. The following histogram presents the number of trials it took each student to memorize the number. 1 2 3 4 5 6 7 5 9 Number of Trials How many students memorized the number in three trials or less