Victory for the ACT Student Text 15e

R EVIEW • 273

6.  –Š‡ ϐ‹‰—”‡ „‡Ž‘™ ‹• ƒ ’‘”–‹‘ ‘ˆ –Š‡ ȋ x , y ) coordinate plane. If each small square has an area of 1 and the coordinates of point P are (3,7), what are the ( x , y ) coordinates of point Q ? F. (5,6) G. (1,10) H. (6,9) J. (6,5) K. (5,10) 7. The average of 8 numbers is 6; the average of 6 other numbers is 8. What is the average of all 14 numbers? A. 6 B. 6 7 6 C. 7 D. 7 7 2 E. 8 7 1 8. Which of the following is the matrix product of . . . 0 5 1 3 2 0 25 1 5 = G and 8 1 12 0 2 6 R T SSSSSSSS V X

9. Doreen can wash her car in 15 minutes, while her younger brother Dave takes twice as long to do the same job. If they work together, how many minutes will the job take them? A. 5 B. 7 2 1 C. 10 D. 22 2 1 E. 30 10.  –Š‡ ϐ‹‰—”‡ „‡Ž‘™ǡ –Š‡ •‹†‡• ‘ˆ –Š‡ Žƒ”‰‡ square are each 14 inches long. Joining the midpoints of each opposite side forms 4 smaller squares. What is the value of y , in inches?

The Cambridge Edge When multiplying matrices, don't do more work than is necessary to answer the item. If matrix A has dimensions m n # and matrix B has dimensions , p q # the product AB will have dimensions . m q # The product BA will have dimensions p n # . Eliminate any choices that don't contain the correct number of columns or rows. Then, determine only as many elements in the product matrix necessary to choose between the remaining choices.

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