Home / 920.78-1,270.50-640.58

Finding the Fourth Proportional to 920.78, 1,270.50 and 640.58

Calculator

Solution

The fourth proportional to 920.78, 1,270.50 and 640.58 is: 883.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.78 : 1,270.50 = 640.58 : x
  2. Step 2: Convert to fraction form
    920.78/1,270.50 = 640.58/x
  3. Step 3: Cross multiply
    920.78x = 1,270.50 × 640.58
  4. Step 4: Simplify right side
    920.78x = 813,856.89
  5. Step 5: Solve for x
    x = 813,856.89/920.78
  6. Step 6: Final answer
    x = 883.88

Related Problems

Find fourth proportional to 460.39, 635.25 and 320.29
Half scale
Find fourth proportional to 1,841.56, 2,541 and 1,281.16
Double scale
Find fourth proportional to 921.78, 1,271.88 and 641.58
Similar ratio
Find fourth proportional to 1,381.17, 1,905.75 and 960.87
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.