Step-by-step explanation:






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The speed of wind and speed of plane in still air are 23 and 135
km/h respectively.
<u>Step-by-step explanation:</u>
Let the speed of wind and speed of plane in still air are w and p km/h respectively.
The effective speed on onward journey was
................(1)
The effective speed on return journey was
..............(2)
Adding equation (1) and equation (2) we get,
⇒ 
⇒ 
⇒ 
Putting value of
in
we get:
⇒ 
⇒ 
⇒ 
Therefore ,The speed of wind and speed of plane in still air are 23 and 135
km/h respectively.
Answer:
They spend at least 69.48 minutes reading the paper.
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:

For the 10% who spend the most time reading the paper, how much time do they spend?
They spend at least X minutes, in which X is the value of X when Z has a pvalue of 0.90. So it is X when Z = 1.28.




They spend at least 69.48 minutes reading the paper.
The number of soccer players is 4 times the number of volleyball players.