Find the area under the standard normal curve between z=0.45 and z=1.13

2-digit numbers less than 91 which are 1 less than a multiple of 10

Find the maximum value of p= 4x + 5y subject to the following constraints :

Aremote-controlled boat can travel at 4 feet per second in calm water. the boat traveled 48 feet with the current, and then it traveled 16 feet against the current in the same amount of time. how fast is the current?