A pebble is dropped into a calm pond, causing ripples in the form of concentric circles. The radius (in feet) of the outer ripple is , wheretis the time in seconds after the pebble strikes the water. The area of the circle is given by the function 

style="font-size:12pt;vertical-align:middle;" />. Find and interpret .

?



A. ;  represents the area of the circle  at time t.
B. ;  represents the area of the circle  at time t.
C. ;  represents the area of the circle  at time t.
D. ;  represents the area of the circle at time t.
E. ;  represents the area of the circle  at time t.

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Answer: D

Mathematics

Find the indicated cardinal number.Find n(D × B) given that B = {1, 3} and D = {7, 8, 9, 10}.

A.

8

B. 12
C. 16
D. 7

Is the following a statement? What is its truth value?The state of Illinois is in North America.

A. Statement. The truth value is false. B. Statement. The truth value is true. C. Not a statement. The sentence cannot be answered true or false.

Translate using numbers and symbols.The difference of nineteen and fifteen

A. 15 - 19 B. 19 - x C. 19 - 16 D. 19 - 15

Solve the problem.A turntable rotates at 54 revolutions per minute. What is its angular speed in radians per second?

A. ? radians/second
B. ? radians/second
C. ? radians/second
D. ? radians/second