The equation $y = -16t^2 - 18t + 405$ describes the height (in feet) of a ball thrown downward at 18 feet per second from a height of 405 feet from the ground, as a function of time $t$, in seconds. in how many seconds will the ball hit the ground? express your answer as a decimal rounded to the nearest tenth.

After 4.5 seconds the ball reaches ground.

Step-by-step explanation:

We equation of motion given as y = -16t²-18t+405,

We need to find in how many seconds will the ball hit the ground,

That is we need to find time when y = 0

                        0 = -16t²-18t+405

                       16t²+18t-405 = 0

Negative time is not possible, hence after 4.5 seconds the ball reaches ground.

solution:

as, mean is defined as sum of all the observations divided by total number of observations.

and , median is mid value of the data whether arranged in ascending order or descending order.

consider, roadsters:

2,3,4,5,6,7,8,9

mean =

also, median= , because number of observations is even, so median is mean of two mid values.

now, coming to bandits

2,3,4,5,6

mean =  

median = 4, as number of observations is odd.

so, roadsters has greater median as well mean than bandits.

→option a is true about the repairs performed on 2 types of cars:

bandits have lower median and mean than roadsters.