X is the center of the circle
Answer:
14/20 or .7 or 70%
Step-by-step explanation:
Total Number of cards: 20
Number of Red cards: 6
The leftover cards: 20 -6 = 14
The probability of not getting a red = 14/20
14/20 as a decimal = 14/20 = 70/100 = .7
14/20 as a percent = 14/20 = 70/100 = 70%
14). (Take π value as 22/7)
circumference = 66in
2πr = 66in
2×22/7×r = 66
r = 66×7/2×22
r = 21/2in
d = 2r => d = 2×21/2
therefore diameter of the circle = 21in
15). (Take π value as 3.14)
Circumference = 3.14m
2πr = 3.14m
2×3.14×r = 3.14
r = 3.14/3.14×2
r = 1/2m
Therefore the radius of the circle = 0.5m
16). (Take π value as 22/7)
Circumference = 33km
2πr = 33km
2×22/7×r = 33
r = 33×7/2×22
r = 21/4
d = 2r
d = 2×21/4
d = 21/2km
Therefore the diameter of the circle = 10.5km
Let 
be the 20 marks of the boys, and 
be the 10 marks of the girls.
We know that the global mean was 70, meaning that
Multiplying both sides by 30 we deduce that the sum of the scores of the whole classroom is
By the same logic, we work with the marks of the boys alone: we know the average:
And we deduce the sum of the marks for the boys:
Which implies that the sum of the marks of the girls is 
And finally, the mean for the girls alone is
