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Finding the Fourth Proportional to 780.96, 1,075.26 and 647.64

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Solution

The fourth proportional to 780.96, 1,075.26 and 647.64 is: 891.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.96 : 1,075.26 = 647.64 : x
  2. Step 2: Convert to fraction form
    780.96/1,075.26 = 647.64/x
  3. Step 3: Cross multiply
    780.96x = 1,075.26 × 647.64
  4. Step 4: Simplify right side
    780.96x = 696,381.39
  5. Step 5: Solve for x
    x = 696,381.39/780.96
  6. Step 6: Final answer
    x = 891.70

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.