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Finding the Fourth Proportional to 780.57, 1,170.62 and 643.28

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Solution

The fourth proportional to 780.57, 1,170.62 and 643.28 is: 964.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.57 : 1,170.62 = 643.28 : x
  2. Step 2: Convert to fraction form
    780.57/1,170.62 = 643.28/x
  3. Step 3: Cross multiply
    780.57x = 1,170.62 × 643.28
  4. Step 4: Simplify right side
    780.57x = 753,030.58
  5. Step 5: Solve for x
    x = 753,030.58/780.57
  6. Step 6: Final answer
    x = 964.72

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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.