Ok so the average is 50
average of x number of things is
(add value of all things)/x=average
4 test scores needed
so divide by 4
3 test scores ar known
average is 50
x= missing score
(43+48+42+x)/4=50
times 4 both sides
133+x=200
minus 133 both sides
x=67
a score of 67 is needed
The probability that none of the four have been vaccinated is
(1-0.63)^4 = 0.01874161
The probability that at least one has been vaccinated is the complement of this,
≈0.9813
Multiply all the numbers by 2 first, so 12 yards 18 ft 8 in. After that, you simplify. There are three feet in a yard, so in eighteen feet there are 6 yards. That makes 18 yards and 8 in