Help My grades are slipping!

Which statement is not always true for a parallelogram? (a) opposite sides are congruent. (b) diagonals bisect each other. (c) it has 4 congruent angles. (d) consecutive angles are supplementary.

Analyze the data sets below. data set a 25,25,25,26,26,26,27,28,28,29,30,31,31,32,33,33,34,35,35,35 data set b 25,25,25,26,26,26,26,27,27,27,27,28,28,29,29,30,31,31,32,34 which of the following statement are true? select all that apply. a. data set a is relatively symmetric and data set b is skewed left. b.the means of the data sets are within 3 units from eachother. c.the data sets have the same standard deviation. d.the mean of data set a is 27.95 and the mean of data set b is 30. e. the data set b has a higher standard deviation than data set a. f. the mean and median of data set a are close in value.

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?