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Finding the Fourth Proportional to 859.70, 1,289.55 and 643.70

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Solution

The fourth proportional to 859.70, 1,289.55 and 643.70 is: 965.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.70 : 1,289.55 = 643.70 : x
  2. Step 2: Convert to fraction form
    859.70/1,289.55 = 643.70/x
  3. Step 3: Cross multiply
    859.70x = 1,289.55 × 643.70
  4. Step 4: Simplify right side
    859.70x = 830,083.34
  5. Step 5: Solve for x
    x = 830,083.34/859.70
  6. Step 6: Final answer
    x = 965.55

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1.5x scale

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.