Answer: 3/2
Step-by-step explanation:
Answer:
Weights of at least 340.1 are in the highest 20%.
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:

a. Highest 20 percent
At least X
100-20 = 80
So X is the 80th percentile, which is X when Z has a pvalue of 0.8. So X when Z = 0.842.




Weights of at least 340.1 are in the highest 20%.
Answer:
1620
Step-by-step explanation:
(a) (i) In first 4 minutes Mary's speed was 600 / 4 = 150 m / minute
(ii) in last 4 minutes her speed was (1000-600) / 4 = 400/4 = 100 m/min
(b) Marys average speed for the whole journey = 1000/8 = 125 m/min
(c) 200 m
(d) Peter arrived at school after 7 minutes . Mary took 8 minutes. Peter first.
(e) Where they met is given by where the 2 curves intersect. That is at time 6.8 minutes and 880 m from Mary's home
(f) At t= 4 dsitance between then is 600 - 400 = 200 m