- One cent is a a hundredth of R , so R 1 = 100 c. Every hour Lerato earns "R\\, 18 = 18 \\cdot 100 \\, c= 1800 \\,c". Now we need to find how much cents she is earning per second. One hour is 60 minutes, every minute is 60 seconds. So there is 3600 s in 1h.
Lerato earns
"\\displaystyle 1800\\frac{c}{h} = 1800 \\cdot \\frac{c}{3600 s} = \\frac{1800}{3600} \\frac{c}{s} = \\frac{1}{2}\\frac{c}{s}"
Answer: 1/2 or 0.5 cent per second.
- Moosa can wash 6 Windows in 21 minutes. How much time does he spend for one window? This is "\\displaystyle \\frac{21}{6}" minutes per window. To wash 10 windows, he needs
"\\displaystyle 10 \\cdot \\frac{21}{6} = \\frac{21 \\cdot 10}{6} = \\frac{21 \\cdot 5}{3} = 7 \\cdot 5 =35" minutes.
Answer: 35 minutes.
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