Mean + time - practice problems
Number of problems found: 191
- The usage
The battery usage time installed in a particular smartphone has a Normal distribution with a mean of 25.2 hours and a standard deviation of 7.5 hours. What is the probability of usage time greater than 32? - The number 9
The number of minutes it took Jim to ride his bike to school for each of the past six days was 21, 18, 16, 19, 24, and 19. Find the mean number of minutes. - A meteorologist
A meteorologist calculated that the average temperature over the last four years dropped a total of 20 degrees. What integer represents the average change in the temperature per year? - Bulb life
Tests show that the lives of light bulbs are normally distributed with a mean of 750 hours and a standard deviation of 75 hours. Find the probability that a randomly selected light bulb will last between 675 and 900 hours.
- A Gallup
A Gallup poll investigated whether adults in Mumbai preferred staying at home or going out as their favorite way of spending time in the evening. Out of the 500 adults, the majority of adults (70%) indicated that staying at home was their favorite evening - Together 83245
Jarka and Jana decided to decorate their common room. If Jarka painted it alone, it would take her 4 hours, and Jane 3 hours. How long would they paint the room if they painted together? - Corrects 83017
The new teacher corrects papers for 9 hours, and the older one fixes them in 6 hours. How much will they repair together? - Together 82965
An older digger would dig a ditch by himself in 6 hours. A younger digger can handle the same trench in 3 hours. How long would it take them to dig if they worked together? - Companies 82884
The K+S company will mow the meadow in ten hours. The Kosačka company mows the meadow in six hours. How many hours would these companies mow one such meadow if they worked together?
- Simultaneously 82806
An empty tank is filled with inflow in 30 minutes. A full tank is emptied in 75 minutes with an open drain. How long does it take for an empty tank to fill up if both the inlet and outlet are open simultaneously? - Excavators 82208
Two excavators dig a pit in 12 days. How much shorter will this job take if 8 excavators dig the hole? In 3 or 9 days? - Throughout 82075
In the metro, trains run in one direction at the same speed and the same intervals. Yesterday, there were 24 trains throughout the day. More trains will run today, as the time interval between trains will be shorter by 20%. How many more trains will there - Together 82027
Eva sews a costume in 6 hours, Ivana in 8 hours, and Monika in 4 hours. How long will it take them to make the costume if they work together? - Makarska 81876
The motor boat departs from Baška Voda at 19:15 and arrives in Makarska at an average speed of 30 km/h at 20:00. However, a group of tourists from Germany must be in Makarska a third of the time earlier. What should the average speed of the boat be?
- Basement 81681
After the flood, the Nováks would pump water out of the basement with one pump in 120 minutes, the second in 300 minutes, and the third in 600 minutes. How many minutes will it take them to pump the water out of the basement if they use all the pumps at o - Apartment 81654
A woman cleans an apartment in 8 hours and a man in 10 hours. How many hours will they clean together? - Calculate 81492
Jirka went on a moped for a three-day trip. He drove 90 km on the first day, 30 km on the second day, and 60 km on the third day. He always drove at the same average speed and always the whole number of hours. Calculate the average speed if Jirka drove at - Simultaneously 81441
The tank is filled through three openings, A, B, and C. The simultaneously open inlets A and B are filled in 1 hour, inlets A and C in 45 minutes, and inlets B and C in 1.5 hours. How long would it take to fill each inlet separately? - Together 81046
Two painters are painting the factory fence together. If everyone worked alone, the first would finish the job in 16 days, the second in 20 days. When will they finish the work together?
Do you have homework that you need help solving? Ask a question, and we will try to solve it.