12. of the following, which one is an observational study? a. asking hearing-impaired people to try a new style of earphone to get their opinion b. comparing survival rates between treating bone cancer with surgery versus treating it with radiation c. recording the daily output of a balloon factory for 6 months d. polling people on their favorite color i believe it would be 'c', yes?

Find the height of a square pyramid that has the volume of 32 ft.³ and a base lengthof 4 feet

The volume of gas a balloon can hold varies directly as the cube of its radius. imagine a balloon with a radius of 3 inches can hold 81 cubic inches of gas. how many cubic inches of gas must be released to reduce the radius down to 2 inches?

Using pert, adam munson was able to determine that the expected project completion time for the construction of a pleasure yacht is 21 months, and the project variance is 4. a) what is the probability that the project will be completed in 17 months? b) what is the probability that the project will be completed in 20 months? c) what is the probability that the project will be completed in 23 months? d) what is the probability that the project will be completed in 25 months? e) what is the due date that yields a 95% chance of completion?