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Finding the Fourth Proportional to 1,281.18, 1,920.75 and 870.45

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Solution

The fourth proportional to 1,281.18, 1,920.75 and 870.45 is: 1,304.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,281.18 : 1,920.75 = 870.45 : x
  2. Step 2: Convert to fraction form
    1,281.18/1,920.75 = 870.45/x
  3. Step 3: Cross multiply
    1,281.18x = 1,920.75 × 870.45
  4. Step 4: Simplify right side
    1,281.18x = 1,671,916.84
  5. Step 5: Solve for x
    x = 1,671,916.84/1,281.18
  6. Step 6: Final answer
    x = 1,304.98

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.