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Finding the Fourth Proportional to 1,378.16, 2,066.40 and 647.90

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Solution

The fourth proportional to 1,378.16, 2,066.40 and 647.90 is: 971.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.16 : 2,066.40 = 647.90 : x
  2. Step 2: Convert to fraction form
    1,378.16/2,066.40 = 647.90/x
  3. Step 3: Cross multiply
    1,378.16x = 2,066.40 × 647.90
  4. Step 4: Simplify right side
    1,378.16x = 1,338,820.56
  5. Step 5: Solve for x
    x = 1,338,820.56/1,378.16
  6. Step 6: Final answer
    x = 971.46

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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.