Solve each pair of simultaneous equations by substitution method

You were told that the amount of time lapsed between consecutive trades on the new york stock exchange followed a normal distribution with a mean of 15 seconds. you were also told that the probability that the time lapsed between two consecutive trades to fall between 16 to 17 seconds was 13%. the probability that the time lapsed between two consecutive trades would fall below 13 seconds was 7%. what is the probability that the time lapsed between two consecutive trades will be between 14 and 15 seconds?

The ratios 3: 9, 4: 12, 5: 15, and 6: 18 are a pattern of equivalent ratios in the ratio table. which is another ratio in this pattern?

What are the solutions of the equation? 6x^2 + 11x + 4 = 0 a. 4/3, 1/2 b. -4/3, -1/2 c. 4/3, -1/2 d. -4/3, 1/2