How many commuters must be randomly selected to estimate the mean driving time of Chicago commuters? We want 90% confidence that the sample mean is within 4 minutes of the population mean, and the population standard deviation is known to be 12 minutes.

The number of commuters to be randomly selected to estimate the mean driving time of Chicago commuters is 25

Step-by-step explanation:

At  90% confidence

we have

Minimum sample size, n given by

Where:

c = Confidence level = 90%

σ = Standard deviation = 12 minutes

E = Maximum error in estimate = minutes

- = 1.64 and = 1.64

Therefore, = 0.51994 and therefore, n is given by

= 24.2064

As we are talking of population, we round to the next whole number, thus;

n = 25 commuters.

so a parallelogram is just like a square base times height. multiply 40 and 39 to get 1560 inches.

a triangle is base times height divided by two. so multiply 7.9 and 5 and then divide it by 2 to get 19.75inches.

the kite can be split into two separate triangles and added together to get the total area. 30 x 4 /2 which equals 60. make sure to double it for the two triangles making 120.