Solve the problem.From a point on a river, two boats are driven in opposite directions, one at 7 miles per hour and the other at 12 miles per hour. In how many hours will they be 38 miles apart?
A. 1 hr
B. 4 hr
C. 2 hr
D. 3 hr
Answer: C
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Solve the problem involving direct translation.The product of 4 and the sum of a number and 5 is equal to the difference of twice the number and 9. Find the number.
A. 4x + 5 = 9 - 2x; x = 7
B. 4(x + 5) = 2x - 9; x = - 
C. 4(x + 5) = 9 - 2x; x = - 
D. 4x + 5 = 2x - 9; x = - 7
Solve the problem.The distance D in feet that an object has fallen after t seconds is given by D(t) = 16t2. (i) Evaluate D(2) and D(3). (ii) Calculate the average rate of change of D from 2 to 3. Interpret the result.
A. (i) 64, 144 (ii) 16; the object's average speed from 2 to 3 seconds is 16 ft/sec. B. (i) 32, 48 (ii) 80; the object's average speed from 2 to 3 seconds is 80 ft/sec. C. (i) 32, 48 (ii) 16; the object's average speed from 2 to 3 seconds is 16 ft/sec. D. (i) 64, 144 (ii) 80; the object's average speed from 2 to 3 seconds is 80 ft/sec.
Solve.4
= 
A. 
B. - 
C. 
D. - 
Solve the problem.The acidity of a solution can be gauged by measuring the concentration of hydrogen ions in the solution. This ion concentration is usually given in units of moles per liter (mols) and is denoted by [H+]. For distilled water, [H+] ? 10-7 mols indicating that each liter of water contains approximately 10-7 moles of hydrogen ions. The pH of a solution is defined bypH = log10
.Thus the pH of distilled water is about 7. Find the concentration of hydrogen ions, [H+], in a solution having a pH equal to 8.8. Express your answer to three significant digits using scientific notation.
A. 1.58 × 10-9 mols B. 9.44 × 10-1 mols C. 1.51 × 10-4 mols D. 1.58 × 10-8 mols