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
Number of returns = 47
Number of returns that contain errors = 5
Number of returns that does not contain error = 47 - 5 = 42
P(selecting none that contains error in the unreplaced selection) = 42/47 x 41/46 x 40/45 = 68880 / 97290 = 0.708
option C is the correct answer.
Answer:
12
Step-by-step explanation:
64+52=118 studied in the cafeteria or lounge
but 20 studied in both, so 118-20 = 98 studied there in total
110 -98 = 12
