Home / 780.87-1,171.17-428.60

Finding the Fourth Proportional to 780.87, 1,171.17 and 428.60

Calculator

Solution

The fourth proportional to 780.87, 1,171.17 and 428.60 is: 642.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.87 : 1,171.17 = 428.60 : x
  2. Step 2: Convert to fraction form
    780.87/1,171.17 = 428.60/x
  3. Step 3: Cross multiply
    780.87x = 1,171.17 × 428.60
  4. Step 4: Simplify right side
    780.87x = 501,963.46
  5. Step 5: Solve for x
    x = 501,963.46/780.87
  6. Step 6: Final answer
    x = 642.83

Related Problems

Find fourth proportional to 390.44, 585.59 and 214.30
Half scale
Find fourth proportional to 1,561.74, 2,342.34 and 857.20
Double scale
Find fourth proportional to 781.87, 1,172.67 and 429.60
Similar ratio
Find fourth proportional to 1,171.31, 1,756.76 and 642.90
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.