In a certain suburb there are no postal deliveries to street addresses. Each household has a postbox at the local post office. A company wants to send out a questionnaire to a sample of the householders to find out if there is a demand for garden services in the area. A post box number is chosen at random out of the first 10 numbers and then every 20 th number is chosen and the questionnaires placed in these post boxes. This sampling technique is called Select one: a. stratified random sampling. c. availability sampling. d. simple random sampling.

123: Calcola l'area di un cerchio, sapendo che un suo settore circolare di area \( 148 \mathrm{~cm}^{2} \) corrispon- de a un anglo al centro ampio \( 40^{\circ} \). \( \left[1332 \mathrm{~cm}^{2}\right] \)

Ariz is planning to attend college when she graduates from high school four years from now. She has made an arrangement with her father to do the household chores if her dad deposits R3 570,00 at the end of every six months for the next four years into a bank account. The account pays \( 8,5 \% \) interest per annum, compounded semi-annually. Her father pays and additional R5 550,00 into the account for every R3 570,00 deposit he makes. The first deposit will be made six months from now. How much money will there be in the account for Aziz to pay for her college expenses?

Determine the future value of an annuity after ten monthly payments of R600,00 at an interest rate of \( 12 \% \) per annum, compounded monthly.

(a) \( x^{3}+x+8 \)

\( e ^ { x } \cos y d x + ( 1 + e ^ { x } ) \sin y d y = c \)