There is a model boat race at local lake. a boat finished the first 2/5 mile at an average speed of 1/3 mile per minute. the boat still has 3/10 mile left to go and continues at the same speed. which equation can be used to find the boat's total race time from start to finish? a. 1/3x = 3/10 - 2/5
b. 1/3x = 2/5 + 3/10
c. 1/3x = 3/10 - 2/5
d. 1/3x = 2/5 + 3/10

no idea

step-by-step explanation:

idk

step-by-step explanation:

payback

irst, find the z score of a score of 80. this is given by the formula z = (x-u)/o, where x is the score, u is the mean, and o is the standard deviation. this gives

z = (80-78)/12 = 1/6 = .1667

now, find what percentile a z score of 1/6 correlates to in the normal distribution.

a z score of 1/6 = .1667 is equivalent to the 56.36th percentile of the distribution. so the probability a score is over this is 1-.5636 = .4364

the mean of a sample mean is equal to the original mean. however, the standard deviation of a sample mean is equal to the original standard deviation divided by the square root of n (sample size). so the new standard deviation is 12/sqrt(16) = 3.

the new z score is 80-78/3 = 2/3 = .667. this is equivalent to the 74.86th percentile. so the probability that the mean will be greater than this score is 1-.7486 = .2514.

answer is  

d.

3.09

hope you got this right.