Each of the 20 students in Mr. Anderson's class flipped a coin ten times and recorded how many times it landed on tails. How many tails would a student expect to see out of ten tosses? please

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling