Tebygolrwydd - Probability Mae tebygolrwydd yn cael ei ddefnyddio pan gawn sefyllfaoedd lle mae elfen o ansicrwydd yn perthyn iddynt. Probability is used when we have situations in which there is an element of uncertainty. Ceir elfen o ansicrwydd pan gynhelir haparbrofion fel taflu ceiniog, taflu dîs neu ddewis cardiau allan o becyn o gardiau chwarae. Uncertainty can be associated with random experiments such as tossing a coin, throwing a die or dealing cards from a pack of playing cards. Gofod Sampl yw’r enw a roddir ar y set o’r holl ganlyniadau posib mewn haparbrawf. Sample Space is the set of all the possible outcomes of a random experiment.

Enghreifftiau - Examples Wrth daflu dîs cyffredin a chofnodi’r sgôr a geir, y gofod sampl yw S = {1, 2, 3, 4, 5, 6} When throwing an ordinary die and noting the score, the sample space is S = {1, 2, 3, 4, 5, 6} Wrth ddewis cerdyn o becyn o gardiau cyffredin a chofnodi’r siwt, y gofod sampl yw S = {calonau, clwbiau, diamwntiau, rhawiau} If a card is dealt from an ordinary pack of playing cards, and the suit is noted, the sample space would be S = {hearts, clubs, diamonds, spades}

Ymarfer/Exercise 3.1 Mathemateg -Ystadegaeth Uned S1 – CBAC Mathematics Statistics Unit S1 - WJEC Wrth daflu dau ddîs cyffredin a chofnodi cyfanswm y ddwy sgôr a geir, y gofod sampl yw S = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12} If two ordinary dice are thrown and the sum of the scores on each die is noted, the sample space would be S = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}