Relative frequency and expected outcomes
விளையாடிக் கற்றுக்கொள்ளுங்கள்
ஆற்றல் சம்பாதிக்க இந்த கேள்விகளுக்குப் பதிலளியுங்கள், பின்னர் மீன் பிடித்து ஆராயுங்கள். கணக்கு தேவையில்லை.
பாட குறிப்புகள்
Theoretical and experimental probability
- Theoretical probability = number of favourable outcomes ÷ total equally likely outcomes. A fair die gives P(6) = \frac{1}{6}.
- Relative frequency (experimental probability) = number of times the event happened ÷ total number of trials.
- Probabilities lie between 0 (impossible) and 1 (certain), and all outcomes sum to 1: P(A) + P(\text{not } A) = 1.
Relative frequency and the law of large numbers
- Over many independent trials with a stable underlying probability, relative frequency tends to settle near that probability. More trials generally reduce random variation, but do not guarantee a closer estimate at every step or remove systematic bias.
- A spinner landing on red 18 times in 50 spins has relative frequency \frac{18}{50} = 0.36.
Expected outcomes
- Expected number = probability × number of trials. If P(\text{red}) = 0.2 and there are 150 trials, expect 0.2 \times 150 = 30.
- Expected values are averages; actual results vary.
Expected frequencies
Bias and fairness
- If the relative frequencies are very different from equal values over many trials, the die or coin may be biased.
- Compare experimental results to the theoretical probability to judge fairness.
Estimating probabilities
- Use data (e.g. past weather) to estimate probability when outcomes are not equally likely.
ஸ்லைடுகள்
Sign up free to view the lesson slides
Step through every slide for this topic — plus flashcards and revision notes — with a free account.
பயிற்சி கேள்விகள்
இலவச முன்னோட்டம் — 32-இல் 8 கேள்விகள். அனைத்தையும் பார்க்க பதிவு செய்யவும்.
1.What is the probability of an impossible event?
Easy- A0
- B0.5
- C1
- D-1
2.What is P(\text{even}) when a fair die is rolled?
Easy- A\frac{1}{6}
- B\frac{1}{3}
- C\frac{1}{2}
- D\frac{2}{3}
3.A coin lands on heads 30 times in 100 tosses. What is the relative frequency of heads?
Easy- A0.3
- B0.7
- C30
- D0.5
4.If P(\text{rain}) = 0.35, what is P(\text{no rain})?
Easy- A0.65
- B0.35
- C0.45
- D1.35
5.A spinner has P(\text{red}) = 0.2. How many reds do you expect in 150 spins?
Easy- A15
- B20
- C30
- D75
6.A bag has 3 red and 7 blue counters. What is P(\text{red})?
Easy- A\frac{3}{7}
- B\frac{3}{10}
- C\frac{7}{10}
- D\frac{1}{3}
7.In 200 trials an event occurs 50 times. What is the relative frequency?
Easy- A0.25
- B0.5
- C4
- D0.05
8.For independent trials under unchanged conditions, why does a large sample generally give a more reliable probability estimate than a small sample?
Easy- Arandom fluctuations in the relative frequency are typically smaller
- Bit is quicker
- Cit is always exact
- Dthere is no difference
Unlock all 32 questions & more
இந்த தலைப்பிற்கான ஒவ்வொரு கேள்வியையும், ஸ்லைடுகளையும், ஃப்ளாஷ் கார்டுகளையும் மற்றும் திருப்புதல் குறிப்புகளையும் பார்க்க இலவச கணக்கை உருவாக்கவும்.
