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Finding the Fourth Proportional to 1,288.63, 1,778.31 and 764.76

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Solution

The fourth proportional to 1,288.63, 1,778.31 and 764.76 is: 1,055.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,288.63 : 1,778.31 = 764.76 : x
  2. Step 2: Convert to fraction form
    1,288.63/1,778.31 = 764.76/x
  3. Step 3: Cross multiply
    1,288.63x = 1,778.31 × 764.76
  4. Step 4: Simplify right side
    1,288.63x = 1,359,976.53
  5. Step 5: Solve for x
    x = 1,359,976.53/1,288.63
  6. Step 6: Final answer
    x = 1,055.37

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Find fourth proportional to 644.31, 889.15 and 382.38
Half scale
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Double scale
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1.5x scale

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.