Find the circumference of the circle

9cm is the radius how to i figure out the circumference

An example on how to solve age problems in consecutive integers

Seats for Mathematics, Physics and Biology in a school are in the ratio 5 : 7 : 8. There is a proposal to increase these seats by 40%, 50% and 75% respectively. What will be the ratio of increased seats?

What is the surface area of this design? 8in 8in 8in

2 to 10 by __ to get the ratio 4 to 20

Mai 60 meters of 35%.

Let $b$ and $c$ be constants such that the quadratic $-2x^2 + bx + c$ has roots $3+/sqrt{5}$ and $3-/sqrt{5}$. Find the vertex of the graph of the equation $y=-2x^2 + bx + c$.

Jackson earned $60 and put 1 5 of those earnings into his savings account. How much did he put into his savings account?

The table shows the change in temperature each hour for four hours. Find the total change C in temperature. Change in Temperature 1 A. M. - 2 A. M. - 3°F 2 A. M. - 3 A. M. - 2°F 3 A. M. - 4 A. M. - 2°F 4 A. M. - 5 A. M. + 4°F

A pitch will be a strike if its height is between 3.5ft and 5.5ft when it crosses home plate. The pitcher throws the ball from a height of 6ft with an initial vertical velocity of 6ft/s and a horizontal velocity of 120 ft/s.

Express the series 19+23+27 + 31 + 35 + 39 + 43 + 47 using sigma notation.