Standard deviation - practice problems - page 6 of 7
Number of problems found: 128
- Stoaches
Stoaches are fictional creatures distantly related to bigfoot and yeti. Stoach weights are normally distributed, with a mean of 904 g and a standard deviation of 104 g. State the probability that the sample mean of a random sample of 36 stoach weights exc - Lesson variability comparison
In September, students missed the following number of lessons: Girls: 2; 0; 7; 8; 2; 2; 4; Boys: 4; 4; 0; 3; 10; 3; 8; Compare the variability of both statistical files. - Customer satisfaction probability Let the random variable ξ represent the number of satisfied customers. The probability of a satisfied customer for each of the four customers is 7/10. Specify: a) probability distribution, distribution function F(x) and P(-0.5 < ξ < 3.1) b) variance
- In mass
In the mass production of a product, the average dimension is 250 mm, whereas the dimensions of individual products due to inaccuracies in the production fluctuate around this mean value. The dimension of the products has a normal distribution with standa - Lifespan
The lifetime of a light bulb is a random variable with a normal distribution of x = 300 hours, σ = 35 hours. a) What is the probability that a randomly selected light bulb will have a lifespan of more than 320 hours? b) To what value of L hours can the la - Average height
There are twice as many girls in the class as there are boys. The average height of girls is 177 cm, and boys 186 cm. What is the average height of students in this class? - Elections 3 From a randomised sample of 500 voters, 140 expressed that they consider the protection of the environment to be the most important task of society, and therefore they will vote for the political party which has in its programme the protection of the envi
- Ball bearings One bearing is selected from the shipment of ball bearings. It is known from previous deliveries that the inner bearing radius can be considered a normal N distribution (µ = 0.400, σ2 = 25.10^−6). Calculate the probability that the selected radius will ex
- Life expectancy
The life expectancy of batteries has a normal distribution with a mean of 350 minutes and a standard deviation of 10 minutes. What is the range in minutes 68% of the batteries will last? What is the range in minutes? How long will approximately 99.7% of b - Wage variance deviation
A statistician monitored the variance of monthly wages and found its value to be 640,000. Determine the standard deviation of salaries after a one-off increase of: a) CZK 1,800, b) 5%. - Standard deviation
Find the standard deviation for the following grouped data: Age (years); Number of Persons 0–10; 15 10–20; 15 20–30; 23 30–40; 22 40–50; 25 50–60; 10 60–70; 5 70–80; 10 - Std-deviation Calculate the standard deviation for file: 63,65,68,69,69,72,75,76,77,79,79,80,82,83,84,88,90
- Grade point average
The average GPA is 2.78, with a standard deviation of 0.45. If GPA is normally distributed, what percentage of the students have the following GPAs? Solve for the z-score and report the appropriate percentage: a. Less than 2.30 b. Less than 2.00 c. More t - Statistical Data Analysis
For the statistical file: 2.3; 3.4; 1.8; 3.2; 3.2; 1.9; 3.3; 4.5; 4.3; 5.0; 4.8; 4.3; 4.3; 1.9 Determine the sample variance and the median, and from the empirical distribution function, determine P (2.1 - Bulbs - short lifespan The life of the bulbs has a normal distribution with a mean value of 2000 hours and a standard deviation of 200 hours. What is the probability that the light bulb will last for at least 2100 hours?
- Normal Distribution Probability The waiting time in the buffet is governed by the normal distribution with a mean value of 130 seconds and a variance of 400. What is the probability that someone will wait less than a minute and a half?
- Variability
In the table below, the number of wrong produced goods in two shifts: morning shift: 2; 0; 6; 10; 2; 2; 4; 2; 5; 2; afternoon shift: 4; 4; 0; 2; 10; 2; 6; 2; 3; 10; Compare the variability in both shifts, compare the average number of wrong goods on both - US GDP
Consider the following dataset, which contains the domestic US gross in millions of the top-grossing movies over the last five years. 300,452,513,550,780 I. Find the Mean of the Dataset II. Find the Squared deviation of the second observation from the mea - The little pub
In an unnamed Prague pub, the Czech Trade Inspection (ČOI) measured draft large beers. From thirty measured half-liters, the sample mean was 0.457085 l and the sample standard deviation was 0.00303. Test at the 1% and 5% significance level the hypothesis - Dataset
Data: 11,15,11,16,12,17,13,21,14,21,15,22 Find the dispersion of a given dataset.
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