Answer:
30
Step-by-step explanation:
1/3 of 60 is 20
40 would be left
1/4 of 40 is 10 so 30 would be left
Answer:
The reading speed of a sixth-grader whose reading speed is at the 90th percentile is 155.72 words per minute.
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:

What is the reading speed of a sixth-grader whose reading speed is at the 90th percentile
This is the value of X when Z has a pvalue of 0.9. So it is X when Z = 1.28.




The reading speed of a sixth-grader whose reading speed is at the 90th percentile is 155.72 words per minute.
Answer:
A. 30000
B. 12000
Step-by-step explanation:
Find out how much spectators leave in 1 minute.
1 second = 5
1 minute = 5 x 60 = 300 (60 seconds)
20 minutes = 300 x 20 = 6000
Since there were only 80% of the full capacity of spectators and after minutes it became 60%...
80% - 60% = 20%
20% = 6000
1% = 6000 ÷ 20 = 300
100% = 300 x 100 = 30000
1 minute = 300 spectators leaving
1 hour = 300 x 60 = 18000 (60 minutes)
30000 - 18000 = 12000