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Finding the Fourth Proportional to 643.68, 965.28 and 278.40

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Solution

The fourth proportional to 643.68, 965.28 and 278.40 is: 417.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.68 : 965.28 = 278.40 : x
  2. Step 2: Convert to fraction form
    643.68/965.28 = 278.40/x
  3. Step 3: Cross multiply
    643.68x = 965.28 × 278.40
  4. Step 4: Simplify right side
    643.68x = 268,733.95
  5. Step 5: Solve for x
    x = 268,733.95/643.68
  6. Step 6: Final answer
    x = 417.50

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Double scale
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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.