Given the following hypothesis: h1: 400 h0: 400 h1: 7 10 h0: 10 self-review 10–3 the mean life of a battery used in a digital clock is 305 days. the lives of the batteries follow the normal distribution. the battery was recently modified to last longer. a sample of 20 of the modified batteries had a mean life of 311 days with a standard deviation of 12 days. did the modification increase the mean life of the battery?

An engineer designs a roller coaster so that a car travels horizontally for 162 ft, then climbs 127 ft at an angle of 31.0° above the horizontal. it then moves 127 ft at an angle of 46.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

Polly is pushing a box across the floor with a force of 30 n. the force of gravity is –8 n, and the normal force is 8 n. which value could describe the force of friction if polly could not move the box?

Gather reliable information to brent make his decision. to gather this information, use newspapers, call insurance companies or look at their web sites, and review consumer magazines and web sites. also, look at the manufacturer web site or for information about gas mileage. list the sources you use and take notes.