Complete question :
The 100m dah times in the girl's track meet were normally distributed with a mean of 13 seconds and a standard deviation of 0.3 seconds.
Lana finished the race in 13.2 seconds . If 84 other girls ran in the event, approximately how many runners did she beat?
Answer:
21 runners
Step-by-step explanation:
Mean, μ = 13 seconds
Standard deviation, σ = 0.3
Lana's race time = 13.2
We find the proportion of runners who had race time above 13.2 ;
Proportion of who had race tune above 13.2
P(x > 13.2)
Obtain the Zscore
Zscore = (x - μ) / σ
Z = (13.2 - 13) / 0.3
Zscore = 0.2 / 0.3 = 0.6667
P(Z > 0.6667) = 0.25239 (Z probability calculator)
This is about 0.25239 * 100 = 25.24% = 25% (nearest percent)
Hence, Number of runners Lana beat = 25% of total runners ;
0.25 * 84 = 21
Hence, Lana beat about 21 runners
The graph looks like this, on the enclosed pic:
One feature is that it's periodic and torn (has cut-off points), meaning the domain is the same as in case of tan(x): x€R and x =/= π/2+πn.
The range equals the range of arcsin(x): -π/2<=y<=π/2 OR y€[-π/2;π/2]
Hope could understand and if it helped! :)
Answer:
36000pi
Step-by-step explanation:
V = 4/3*pi*r^3 so we need to know r
we know surface area, which is 4pi*r^2=3600pi. so we can solve for r
r=30
so v = 4/3*pi*30^3 = 36000pi