if you add 55% and 45% the total is 100% so 45/100 are girls. 35% of the girls scored and A so 35/45 is the probability that it is a girl chosen or 7/9. the probability is 7 out of 9.
Z score = (x -mean) / standard deviation.
For this problem X = 50 cm.
Z-score = (50 - 49.2) / 1.8
Z score = 0.8 / 1.8
Z score = 0.44
Look up 0.44 on a z-score table.
0.44 = 0.6700
0.67 x 100 = 67% will be 50 cm or longer.
1: (pi)5^2 = 78.54 then multiply that by 11 and you get 863.94
2: (pi)13^2= 530.93 then multiply that by 8 and you get 47247.44
3. (pi)18^2= 1017.88 then multiply that by 22 and you get 22393.36
I believe the answer is -27t - 4
