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Finding the Fourth Proportional to 1,280.76, 1,767.54 and 721.20

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Solution

The fourth proportional to 1,280.76, 1,767.54 and 721.20 is: 995.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.76 : 1,767.54 = 721.20 : x
  2. Step 2: Convert to fraction form
    1,280.76/1,767.54 = 721.20/x
  3. Step 3: Cross multiply
    1,280.76x = 1,767.54 × 721.20
  4. Step 4: Simplify right side
    1,280.76x = 1,274,749.85
  5. Step 5: Solve for x
    x = 1,274,749.85/1,280.76
  6. Step 6: Final answer
    x = 995.31

Related Problems

Find fourth proportional to 640.38, 883.77 and 360.60
Half scale
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Double scale
Find fourth proportional to 1,281.76, 1,768.92 and 722.20
Similar ratio
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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.