PLEASE HELP!! Directions: Find the sum for each of the following arithmetic series below. Use the summation formula to find the sums.

1. Find the sum of the first 21 terms in a series where a = 20 and t21= 400.

2. Find the sum of the first 100 terms in a series where a = 0 and t100= 99.

3. Find the sum of the first 50 terms in a series where a = 4 and t50= 196.

Which of the following correctly justifies statement four of the two column proof? a. corresponding angles theorem b. transitive property of equality c. vertical angle theorem d. substitution property of equality

Suppose that 3% of all athletes are using the endurance-enhancing hormone epo (you should be able to simply compute the percentage of all athletes that are not using epo). for our purposes, a “positive” test result is one that indicates presence of epo in an athlete’s bloodstream. the probability of a positive result, given the presence of epo is .99. the probability of a negative result, when epo is not present, is .90. what is the probability that a randomly selected athlete tests positive for epo? 0.0297

Kai walked one and two-thirds of a mile on saturday and four and one-sixth of a mile on sunday. how many miles did kai walk?