Answer:
Step-by-step explanation: 1ft=12in
1.5*12=18in
18-18=0in
100 times
Step-by-step explanation: vibration per second: 50 times
vibration for 2 seconds; 50*2=100 times
x= -1.938404987
Solution in picture
to find midpoint, find the mean.
add the numbers together and divide by the amount of numbers there is:
10 + 20 = 30
30/2 = 15
15 is your answer
hope this helps