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If $$\frac{a}{b}{\text{ = }}\frac{2}{3}$$   and $$\frac{b}{c}{\text{ = }}\frac{4}{5}{\text{,}}$$   then the ration $$\frac{{a + b}}{{b + c}}$$   equal to?

A. $$\frac{{20}}{{27}}$$

B. $$\frac{{27}}{{20}}$$

C. $$\frac{6}{8}$$

D. $$\frac{8}{6}$$

Answer: Option A

Solution(By Examveda Team)

$$\eqalign{ & \frac{a}{b}{\text{ = }}\frac{2}{3}{\text{ and }}\frac{b}{c}{\text{ = }}\frac{4}{5}\,\,\left( {{\text{Given}}} \right) \cr & or\,\frac{c}{b} = \frac{5}{4} \cr & \frac{{a + b}}{{b + c}} \cr & = \frac{{b\left( {\frac{a}{b} + 1} \right)}}{{b\left( {\frac{c}{b} + 1} \right)}} \cr & = \frac{{\frac{a}{b} + 1}}{{\frac{c}{b} + 1}} \cr & = \frac{{\left( {\frac{2}{3} + 1} \right)}}{{\left( {\frac{5}{4} + 1} \right)}} \cr & = \frac{{\frac{2 + 3}{3}}}{{\frac{{5 + 4}}{4}}} \cr & = \frac{{5 \times 4}}{{3 \times 9}} \cr & = \frac{{20}}{{27}} \cr & \therefore \frac{{a + b}}{{b + c}} = \frac{{20}}{{27}} \cr & {\bf{Alternate:}} \cr & a{\text{ }}\,\,\,{\text{ }}\,{\text{ }}\,\,\,\,{\text{ }}b{\text{ }}\,\,\,\,{\text{ }}\,\,\,\,{\text{ }}\,\,\,{\text{ }}c \cr & {2_{ \times \left( 4 \right)}}\,\,\,\,\,{\text{ }}{3_{ \times \left( 4 \right)}} \cr & \,{\text{ }}\,{\text{ }}\,\,\,\,\,\,\,\,\,\,\,\,\,{4_{ \times \left( 3 \right)}}{\text{ }}\,\,\,\,\,\,{5_{ \times \left( 3 \right)}} \cr & \overline {\underline {8{\text{ }}\,\,\,\,\,\,\,\,\,\,\,{\text{ }}12{\text{ }}\,\,\,\,\,\,\,\,\,\,{\text{ }}15\,\,\,\,} } \cr & \therefore \frac{{a + b}}{{b + c}} = \frac{{8 + 12}}{{12 + 15}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \frac{{20}}{{27}} \cr} $$

This Question Belongs to Arithmetic Ability >> Algebra

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Comments ( 6 )

  1. Vaishnavi Boje
    Vaishnavi Boje :
    3 years ago

    2:3 3
    4 4:5
    8:12:15
    8+12/12+15

  2. Sudhansu Patra
    Sudhansu Patra :
    3 years ago

    a : b = 2 : 3
    b : c = 4 : 5
    --------------
    a = 2×4
    b = 4×3
    c = 3×5

  3. Md Maruf
    Md Maruf :
    3 years ago

    a:b = 2: 3
    b:c = 4:5
    a:b:c = 8:12:15
    now
    8+12/12+15
    = 20/27

  4. Ataur Rahman
    Ataur Rahman :
    3 years ago

    Excellent

  5. Galat Baat
    Galat Baat :
    4 years ago

    all of your question are very GOOD..............!

  6. Himansu Seth
    Himansu Seth :
    4 years ago

    The formula is not understanding

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