8th Class Mathematics Sample Paper Mathematics Sample Paper - 8

  • question_answer
    A photograph of a bacteria enlarged 50/000 times attains a length of 5 cm as shown in the diagram, what is the actual length of the bacteria? If the photograph is enlarged 20/000 times only, what would be its enlarged length?

    Answer:

    Let the photograph of bacteria be enlarged x times and length be y cm. As the bacteria enlarged increases, the length also increases in the same ratio. It is a case of direct proportion, i.e., \[\frac{{{x}_{1}}}{{{y}_{1}}}=\frac{{{x}_{2}}}{{{y}_{2}}}\]
    x (times) 20,000 50,000
    Y (cm) X 5
    We have,           \[\frac{20,000}{x}=\frac{50,000}{5}\]
    \[\Rightarrow \]               \[x=\frac{20,000\times 5}{50,000}\]
    = 2 cm
    Thus, enlarged length is 2 cm
    and,       actual length of the bacteria
    \[=\frac{length}{enl\arg ed\,\,\,time}\]
    \[=\frac{5}{50,000}={{10}^{-4}}\]cm
         


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