Home / 643.71-965.21-258.75

Finding the Fourth Proportional to 643.71, 965.21 and 258.75

Calculator

Solution

The fourth proportional to 643.71, 965.21 and 258.75 is: 387.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.71 : 965.21 = 258.75 : x
  2. Step 2: Convert to fraction form
    643.71/965.21 = 258.75/x
  3. Step 3: Cross multiply
    643.71x = 965.21 × 258.75
  4. Step 4: Simplify right side
    643.71x = 249,746.79
  5. Step 5: Solve for x
    x = 249,746.79/643.71
  6. Step 6: Final answer
    x = 387.98

Related Problems

Find fourth proportional to 321.86, 482.60 and 129.38
Half scale
Find fourth proportional to 1,287.42, 1,930.41 and 517.50
Double scale
Find fourth proportional to 644.71, 966.70 and 259.75
Similar ratio
Find fourth proportional to 965.57, 1,447.81 and 388.13
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.