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Finding the Fourth Proportional to 661.60, 992.40 and 643.60

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Solution

The fourth proportional to 661.60, 992.40 and 643.60 is: 965.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.60 : 992.40 = 643.60 : x
  2. Step 2: Convert to fraction form
    661.60/992.40 = 643.60/x
  3. Step 3: Cross multiply
    661.60x = 992.40 × 643.60
  4. Step 4: Simplify right side
    661.60x = 638,708.64
  5. Step 5: Solve for x
    x = 638,708.64/661.60
  6. Step 6: Final answer
    x = 965.40

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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.