Suppose that the lifetimes of TV tubes are normally distributed with a standard deviation of 1.1 years. Suppose also that exactly 25% of the tubes die before 4 years. Find the mean lifetime of TV tubes. Carry your intermediate computations to at least four decimal places. Round your answer to at least one decimal place.

The swimming pool is open when the high temperature is higher than 20∘c. lainey tried to swim on monday and thursday (which was 33 days later). the pool was open on monday, but it was closed on thursday. the high temperature was 30 ∘c on monday, but decreased at a constant rate in the next 33 days. write an inequality to determine the rate of temperature decrease in degrees celsius per day, d, from monday to thursday.

Cora bought a package of erasers. there are 4 pink erasers and 12 blue erasers. what is the ratio of pink erasers to blue erasers?

Arectangle plot measure 20ft. by 30ft. a 3-ft.-wide sidewalk surrounds it.find the area of the sidewalk.