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Finding the Fourth Proportional to 985.56, 1,470.19 and 821.40

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Solution

The fourth proportional to 985.56, 1,470.19 and 821.40 is: 1,225.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.56 : 1,470.19 = 821.40 : x
  2. Step 2: Convert to fraction form
    985.56/1,470.19 = 821.40/x
  3. Step 3: Cross multiply
    985.56x = 1,470.19 × 821.40
  4. Step 4: Simplify right side
    985.56x = 1,207,614.07
  5. Step 5: Solve for x
    x = 1,207,614.07/985.56
  6. Step 6: Final answer
    x = 1,225.31

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.