20.
$ \eqalign{percentage = \frac{{deel}} {{totaal}} \times 100\% = \frac{{11,4}} {{32}} \approx 35,6\% } $
21.
$ \eqalign{ & 1MB = 10^6 bytes \cr & \frac{{11,4 \times 10^9 }} {{10^6 }} = 1,14 \times 10^4 \cr} $ Er kunnen nog 11.400 foto's bij.
22.
$ \eqalign{ & 1TB = 10^{12} byte \cr & 300MB = 300 \times 10^6 byte \cr & 10^{12} - 300 \times 10^6 = 9,997 \times 10^{11} \cr} $
Naschrift
$ \eqalign{ & A.\,\,\frac{{3 + 5}} {{2 \times 7}} = \frac{8} {{14}} = \frac{4} {7} \cr & B.\,\,2 + 4 \times 32 = 2 + 128 = 130 \cr & C.\,\,\left( { - 1} \right)^7 + 1^7 = - 1 + 1 = 0 \cr & D.\,\,\frac{1} {2} + \frac{1} {3}\left( {2 + 4} \right) = \frac{1} {2} + \frac{1} {3} \times 6 = \frac{1} {2} + 2 = 2\frac{1} {2} \cr & E.\,\,\frac{{\frac{1} {5}\left( {11 + 4} \right)}} {{\frac{1} {2} - \frac{2} {5}}} = \frac{{\frac{1} {5} \times 15}} {{\frac{5} {{10}} - \frac{4} {{10}}}} = \frac{3} {{\frac{1} {{10}}}} = 30 \cr & F.\,\,\frac{1} {6} + \frac{2} {3} \times \frac{1} {4} = \frac{1} {6} + \frac{2} {{12}} = \frac{1} {6} + \frac{1} {6} = \frac{2} {6} = \frac{1} {3} \cr & G.\,\,\left( {\frac{1} {3}} \right)^2 \times 1\frac{3} {5} = \frac{1} {9} \times \frac{8} {5} = \frac{8} {{45}} \cr & H.\,\,\frac{2} {3}\left( {\frac{2} {5} + 1\frac{1} {4}} \right) + \frac{1} {3}\left( {\frac{2} {5} + 1\frac{1} {4}} \right) = \frac{2} {5} + 1\frac{1} {4} = \frac{8} {{20}} + 5\frac{5} {{20}} = 5\frac{{13}} {{20}} \cr} $
Einde
