Need some , studying for parcc anyone else? ; )

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

What is the total surface area of this square pyramid?

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?