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Finding the Fourth Proportional to 985.45, 1,360.20 and 690.79

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Solution

The fourth proportional to 985.45, 1,360.20 and 690.79 is: 953.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.45 : 1,360.20 = 690.79 : x
  2. Step 2: Convert to fraction form
    985.45/1,360.20 = 690.79/x
  3. Step 3: Cross multiply
    985.45x = 1,360.20 × 690.79
  4. Step 4: Simplify right side
    985.45x = 939,612.56
  5. Step 5: Solve for x
    x = 939,612.56/985.45
  6. Step 6: Final answer
    x = 953.49

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.