The answer would be 21 because its the same length as the other side.
C=7n because
28 divided 4 is 7
7 is the proportional
The answer is 1:11. After it being simplified from 6:66. Hope this helps.
We have
Mean, μ = 25 minutes
Standard Deviation, σ = 6.1
X = 30 minutes
The probability we are looking for is shown in the first diagram; it's the area on the right of X=30
We need to standardized the value X=30 using the formula


rounded to two dp
The z-table is shown on the second diagram only gives the probability when P(Z<z), so to work out the probability when P(Z>z), we do 1-P(Z<z)
P(Z>0.82) = 1 - P(Z<z) = 1 - 0.7939 = 0.2061