Photocopier

A photocopier enlarges a picture in the ratio of 7:4. How many times will a picture of size 6cm by 4cm be enlarged to fit on a 30cm by 20 cm page?

Correct answer:

n =  2.876

Step-by-step explanation:

$$\begin{gathered} a_1=6\text{cm} \\ {a}_2=30\text{cm} \\ k=7/4=\frac{7}{4}=1\frac{3}{4}=1.75 \\ {a}_2=k^n\cdot a_1 \\ {a}_2/a_1=k^n \\ n=\log (a_2/a_1)/\log k=\log (30/6)/\log 1.75=2.876 \end{gathered}$$

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