Let X represent a random variable representing the birth weights of babies, and let x be the required cut-off, then
P(X < x) = 0.02
P(z < (x - 3419)/494) = 0.02
1 - P(z < (3419 - x)/494) = 0.02
P(z < (3419 - x)/494) = 1 - 0.02 = 0.98
(3419 - x)/469 = 2.04
3419 - x = 956.76
x = 3419 - 956.76 = 2462.24
Therefore, the weight to be used as cut-off is 2462.24 g
Here, all we need to do is subtract.
5 is the total.
5 - 2.25 = 2.75
2.75 - 1.6 = 1.15
She has 1.15 yards of ribbon left.
