Statistics + reason - practice problems
Number of problems found: 110
- Family survey
A total of 160 families with 4 children each were surveyed with the following results. Boys; 4; 3; 2; 1; 0 Girls ; 0; 1; 2; 3; 4 Families; 7; 50; 55; 32; 16 Let the probability of picking a boy or a girl be 1/2. Let P=boy, Q=girl. What is the probability - A biologist
A biologist knows that the average length of a leaf of a certain plant is 4 inches. The standard deviation of the population is 0.6 inches. A sample of 20 leaves of that type of plant given a new type of plant food had an average length of 4.2 inches. At - Chi square
A phone battery manufacturer claims that his battery lives are approximately normally distributed with a standard deviation equal to 0.9 years. Suppose a random sample of 10 of these batteries has a standard deviation of 1.2 years. Do you think that the s - Gas prices 2021
According to the SPP price list in 2021, the price of natural gas, together with its supply, is as follows: D1 - we cook. Fix 3.34 euros/month and 0.0479 euros/kWh (1 cubic meter of gas is approximately 10.555 kWh. It is called combustion heat and changes
- Distribution 55071
Five men drive to work together; 2 have a Škoda car, and the others have an Opel, Seat, and Hyundai. They always randomly choose which car to drive. Each of the five cars has an equal chance. The random variable X determines how many days the same charact - Germination 55283
The supplier of spruce seeds for our nursery declares a germination rate of 80% for his goods. Verify this statement based on an experiment in which only 70 seeds germinated out of 100 randomly selected seeds. - Jacob 2
Jacob took five summative tests in Mathematics during the first quarter, each with a maximum score of 100. Jacob's five integer test scores have a mean of 85, a median of 87, and a mode of 92. What is Jacob's lowest possible score from one of his five tes - Average monthly salary
A total of 10 teachers work at one small school in Moravia. The monthly salary of each is 21,500 CZK or 21,800 CZK or 22,500 CZK, according to their education and age. The average monthly salary for this school's teacher is 21 850 CZK. How many teachers o - Enterprise and wages
The enterprise operates a total 162 workers, and their average salary is M dollars. If the company has hired an additional 18 employee whose average wage would be the S dollars, it will reduce the overall average salary by 3.6%. Calculate the value of the
- Target
Peter, Martin, and Jirka were a fire in a particular target, with only three fields with values of 12, 18, and 30 points. All boys were firing with the same number of arrows, and all the arrows hit the target, and the results of every two boys differed by - Probability 64174
The banker deals, on average, with five clients a day. Find the probability that the number of clients (in one day) will be greater than 4. - Mathematics 7806
Janko has committed that his average grade in mathematics will be exactly 2 at the end of the semester. However, so far, he has received grades 3 and 4. He knows that by the end of the year, he will receive four more grades from the tests. What are the wo - Young mathematician
One young mathematician was bored again. He found that the average age of people in the room where the seminar equals its count. Then his 29-year-old brother entered the room. Even then, the average age of all present was the same as the count of people. - Energy saving
They released three different independent inventions saving 15%, 17%, and 16% energy. Some considered that while the use of these inventions, the total savings will be 15% + 17% + 16% = 48%. Is this true? How much will the percent of energy save all three
- Beer tapping
When checking compliance with the beer tapping, it was found that 60% of the offered beers were underfilled. The others were fine. Thus, instead of 0.5 l, the volume was 4.4 deciliters on average. What was the volume of one average underfilled beer? - In the
In the 6th class, the average half-year mark in physics was 1.7. At the end of the year, Maťo improved his mark from 2 to 1, Ivanka from 3 to 2, and Elenka from 4 to 2. Pavlík worsened his mark from 3 to 4. The average mark of the whole class thus improve - Average 66794
Look for three numbers with an average of 2000. The middle number is 2000 - Mathematicians 11761
The top five mathematicians in the class took on the teacher's help calculating the paper's average grade. They dictated the following results: Mischa: "I came up with 3.30. " Dasha: "That's weird because it worked out precisely 3.45. " Jana: "You probabl - Marks at school
There are 30 students in the class. Five students in the class had a mark of three or triple at the end of the math certificate, and the other students had a mark of one or two. The average mark in all students' mathematics in the class at the end of the
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