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Finding the Fourth Proportional to 1,138.76, 1,571.47 and 641.45

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Solution

The fourth proportional to 1,138.76, 1,571.47 and 641.45 is: 885.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.76 : 1,571.47 = 641.45 : x
  2. Step 2: Convert to fraction form
    1,138.76/1,571.47 = 641.45/x
  3. Step 3: Cross multiply
    1,138.76x = 1,571.47 × 641.45
  4. Step 4: Simplify right side
    1,138.76x = 1,008,011.57
  5. Step 5: Solve for x
    x = 1,008,011.57/1,138.76
  6. Step 6: Final answer
    x = 885.18

Related Problems

Find fourth proportional to 569.38, 785.74 and 320.72
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.