Zadanie 1.
[tex]15\% \times 220 = \frac{15}{100} \times 220 = \frac{15}{5} \times 11 = \frac{165}{5} = 33[/tex]
Zadanie 2.
[tex]x - 15\% \times x = 425 \\ x - \frac{15}{100} x = 425 \\ 100x - 15x = 42500 \\ 85x = 42500 \\ x = 500[/tex]
Zadanie 3.
126 - używane samochody
49 - nowe samochody
Jaki procent wszystkich samochodów stanowią samochody używane:
[tex] \frac{126}{126 + 49} \times 100\% = \frac{126}{175} \times 100 \% = \frac{126}{7} \times 4\% = \frac{504}{7} = 72\%[/tex]Jakie jest prawdopodobieństwo wylosowania samochodu nowego:
[tex] \frac{49}{175} \times 100\% = \frac{49}{7} \times 4\% = \frac{196}{7} \% = 28\%[/tex]
Zadanie 4.
[tex] \frac{x + y}{2} = 42 \\ \frac{a + b + c + d + e}{5} = 5.8 \\ x + y = 42 \times 2 = 84 \\ a + b + c + d + e = 5.8 \times 5 = 29\\ \frac{x + y + a + b + c + d + e}{2 + 5} = \frac{84 + 29}{7} = \frac{113}{7} = 16 \frac{1}{7} [/tex]
Zadanie 5.
pierwszy miesiąc:
[tex]x + 10\% \times x = x + \frac{10}{100} x = 1 \frac{10}{100} x = 1\frac{1}{10} x[/tex]
drugi miesiąc:
[tex]1 \frac{1}{10}x + 8\% \times 1 \frac{1}{10} x = \\ = 1 \frac{1}{10} x + \frac{8}{100} \times 1 \frac{1}{10} x = \\ = 1 \frac{1}{10} x + \frac{8}{100} \times \frac{11}{10} x = \\ = 1 \frac{1}{10} x + \frac{4}{100} \times \frac{11}{5}x = \\ = \frac{11}{10} x + \frac{44}{500} x = \\ = \frac{550}{500} x + \frac{44}{500} x = \\ = \frac{594}{500} x = \frac{297}{250} x[/tex]
początkowa cena:
[tex] \frac{297}{250} x = 11286 \\ 297x = 11286 \times 250 \\ 297x = 2821500 \\ x = \frac{2821500}{297} = 9500[/tex]
