Combine like terms to simplify the expression $z^3+4z^2+z+z^2+6z+1$ .

A) $14z^9$
B) $z^3+13z^2$
C) $z^3+5z^2+7z+1$
D) $13z^9+1$
E) $z^3+12z^2+1$

A t test is conducted to detect differences between two groups in which participants are tested only once.

Four years ago John borrowed $3,000 from Arlette. The principal with interest at 10% compounded semi-annually is to be repaid six years from the date of the loan. Fifteen months ago, John borrowed another $1,500 for 3½ years at 9% compounded quarterly. John is now proposing to settle both debts with two equal payments to be made 2 and 3½ years from now. What should the payments be if money now earns 8% compounded quarterly?

A chartered bank offers a rate of 5.50% on investments of $25,000 to $59,999 and a simple interest rate of 5.75% on investments of $60,000 to $99,999 in 90 to 365-day GICs. How much more will an investor earn from a single $80,000, 180-day GIC than from two $40,000, 180-day GICs?

Sales have increased by 10% over last year. What percentage less was last year's sales than this year's sales?

One drawback of snowball sampling is friends may recommend friends for the study, and their opinions might be very similar.