Find the value of m so that 15, 25, 27 and m are in proportion.

Class 6Ratio and ProportionRatio and Proportion

Step-by-Step Solution

For 15 : 25 :: 27 :

m

, cross-multiplying gives

15 \times m = 25 \times 27 = 675

, so

m = 675 \div 15 = 45

. Check: 15 : 25 = 3 : 5 and 27 : 45 = 3 : 5. Choosing 675 forgets the final division; 405 multiplies the wrong pair

(15 \times 27)

; 37 adds the difference 25 - 15 = 10 to 27.

Answer: D) 45

If a :

b = c : d

, the four numbers are in proportion. The classic check: the **product of the extremes**

(a \times d)

equals the **product of the means**

(b \times c)

. Example: are 4 : 6 and 6 : 9 in proportion? Cross-multiply:

4 \times 9 = 36, 6 \times 6 = 36

. Equal → yes, in proportion.

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