If np greater than or equals 5np≥5 and nq greater than or equals 5nq≥5, estimate upper p left parenthesis fewer than 5 right parenthesisp(fewer than 5) with nequals=1414 and pequals=0.40.4 by using the normal distribution as an approximation to the binomial distribution; if npless than< 5 or nqless than< 5, then state that the normal approximation is not suitable.

for finding the midpoint of any given 2 pair of points simply add the respective x coordinates with other x coordinate and the y coordinate with other y coordinate and divide them by 2

in your question it will be :

(3+1)/2 for the x coordinate of mid point i.e 2

[8+(-4)]/2 for the y coordinate of midpoint i.e 2

so coordinates of mid point of points (3,8) and (1,-4) will be (2,2)

its a straight line parallel to the time axis