Home / 287.80-428.51-286.20

Finding the Fourth Proportional to 287.80, 428.51 and 286.20

Calculator

Solution

The fourth proportional to 287.80, 428.51 and 286.20 is: 426.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.80 : 428.51 = 286.20 : x
  2. Step 2: Convert to fraction form
    287.80/428.51 = 286.20/x
  3. Step 3: Cross multiply
    287.80x = 428.51 × 286.20
  4. Step 4: Simplify right side
    287.80x = 122,639.56
  5. Step 5: Solve for x
    x = 122,639.56/287.80
  6. Step 6: Final answer
    x = 426.13

Related Problems

Find fourth proportional to 143.90, 214.26 and 143.10
Half scale
Find fourth proportional to 575.60, 857.02 and 572.40
Double scale
Find fourth proportional to 288.80, 430 and 287.20
Similar ratio
Find fourth proportional to 431.70, 642.77 and 429.30
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.