Home / 817.80-1,228.19-428.06

Finding the Fourth Proportional to 817.80, 1,228.19 and 428.06

Calculator

Solution

The fourth proportional to 817.80, 1,228.19 and 428.06 is: 642.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    817.80 : 1,228.19 = 428.06 : x
  2. Step 2: Convert to fraction form
    817.80/1,228.19 = 428.06/x
  3. Step 3: Cross multiply
    817.80x = 1,228.19 × 428.06
  4. Step 4: Simplify right side
    817.80x = 525,737.69
  5. Step 5: Solve for x
    x = 525,737.69/817.80
  6. Step 6: Final answer
    x = 642.87

Related Problems

Find fourth proportional to 408.90, 614.09 and 214.03
Half scale
Find fourth proportional to 1,635.59, 2,456.38 and 856.12
Double scale
Find fourth proportional to 818.80, 1,229.69 and 429.06
Similar ratio
Find fourth proportional to 1,226.69, 1,842.28 and 642.09
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.