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Finding the Fourth Proportional to 780.56, 1,170.49 and 428.93

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Solution

The fourth proportional to 780.56, 1,170.49 and 428.93 is: 643.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.56 : 1,170.49 = 428.93 : x
  2. Step 2: Convert to fraction form
    780.56/1,170.49 = 428.93/x
  3. Step 3: Cross multiply
    780.56x = 1,170.49 × 428.93
  4. Step 4: Simplify right side
    780.56x = 502,051.35
  5. Step 5: Solve for x
    x = 502,051.35/780.56
  6. Step 6: Final answer
    x = 643.20

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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.