¿Carlos ya casi está en edad de ir a la escuela! Con base en la ubicación de su casa, hay 6 escuelas primarias, 3 secundarias y 2 preparatorias a las que tiene la opción de asistir. ¿Cuántos caminos educativos están disponibles para Carlos? Supón que solo asistirá a una de cada tipo de escuela.

Multiply \( (3+8 i)(5-4 i) \)

\[ \quad \begin{array}{l}\text { Multiply } \\ (-8+4 i)(7-3 i)\end{array} \]

De las opciones seleccione la que corres \( 3 x y+49=x^{2}-4 y^{2} \) cuando \( x=7, y=-5.25 \)

Solve the exponential equation for \( t \). Round to three decimal places if necessary. \( e^{t}=68 \)

7. When 3 litres of oil are removed from an upright cylindrical can, the level falls by 10 cm . Find the radius of the can. 8. A solid cylinder of radius 4 cm and length 8 cm is melted down and recast into a solid cube. Find the side of the cube. 9. A solid rectangular block of copper 5 cm by 4 cm by 2 cm is drawn out to make a cylindrical wire of diameter 2 mm . Calculate the length of the wire. 10. Water flows through a circular pipe of internal diameter 3 cm at a speed of \( 10 \mathrm{~cm} / \mathrm{s} \). If the pipe is full, how much water flows from the pipe in one minute? (Answer in litres.) 11. Water flows from a hose-pipe of internal diameter 1 cm at a rate of 5 litres per minute. At what speed is the water flowing through the pipe? 12. A cylindrical metal pipe has external diameter of 6 cm and internal diameter of 4 cm . Calculate the volume of metal in a pipe of length 1 m . If \( 1 \mathrm{~cm}{ }^{3} \) of the metal has a mass of 8 g , find the mass of the pipe.