Statistiek
 

Zouden jullie deze problemen na kunnen kijken.

Alvast bedankt,

Problem 1
Assume that the probability of an increase of the price of a share of KLM the next trading day is 40%. We follow the shares of KLM for 30 trading days after each other. Assume further that the price of a share of KLM is independent from day to day.

a. Calculate the probability that the price of a KLM share increases exactly 7 times (out of 30 days).
0.026

b. Calculate the probability that the price of a KLM share increases 7 times or less. Is this unusual?
0.044, ja aangezien het onder de 5% is.

c. What is the average number of trading days with an increase of a KLM share? What is its standard deviation?
Average = 0.4*30 = 12 dagen
St. dev = sqrt ( 30 * 0.4 * (1 – 0.4)) = 7.2


Problem 2
The production line of an industrial company has been investigated for failures. In the past four weeks the number of daily failures have been counted. The results are:

Number of failures 0 1 2 3
Probability 0.65 0.05 0.10 0.20


a. Calculate the expected number of daily failures.
0.85
b. Calculate the standard deviation of the failures.
1.24
c. Calculate the probability of 14 or more failures in five working days.
0.2 ^ 4 * 0.1 + 0.2^5
Maar volgens het antwoordmodel moet het zijn:
5 * 0.2 ^ 4 * 0.1 + 0.2^5

Wat sowieso fout is, is dat je nergens een berekening bij schrijft.

2a zou bijvoorbeeld moeten zijn: 0*0,65 + 1*0,05 + 2*0,10 + 3*0,20 = 0,85

Bij vraag 1c moet je de wortel uit 7.2 nemen. Voor de rest klopt vraag 1 volgens mij helemaal