TuitionGoWhere Exam Practice (AI) - A-Level Maths H1
Subject: Mathematics (H1)
Level: A-Level
Paper: Practice Paper 2 of 5 (Statistics & Probability Focus)
Duration: 1 hour 30 minutes
Total Marks: 60
Name: __________________________
Class: __________________________
Date: __________________________
Instructions to Candidates
- Write your name, class, and date in the spaces provided.
- Answer all questions.
- Write your answers in the spaces provided in this booklet.
- Give non-exact numerical answers correct to 3 significant figures, or 1 decimal place for angles in degrees, unless a different level of accuracy is specified in the question.
- You are expected to use an approved graphing calculator.
- Unsupported answers from a graphing calculator are allowed unless the question specifically states otherwise.
- Clear presentation in your working is essential.
Section A: Probability and Distributions (20 Marks)
1. A company manufactures smartphone cases. The probability that a case is defective is 0.04. A random sample of 25 cases is selected.
(a) State the distribution of the number of defective cases in the sample, defining any variables used. [1]
(b) Find the probability that exactly 2 cases are defective. [2]
(c) Find the probability that at least 1 case is defective. [2]
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2. The weights of durians sold at a market are normally distributed with mean 1.8 kg and standard deviation 0.3 kg.
(a) Find the probability that a randomly chosen durian weighs more than 2.2 kg. [2]
(b) Find the weight w such that 10% of durians weigh less than w. [2]
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3. Events A and B are such that P(A)=0.4, P(B)=0.5, and P(A∪B)=0.7.
(a) Find P(A∩B). [1]
(b) Determine whether events A and B are independent, giving a reason for your answer. [2]
(c) Find P(A∣B′). [2]
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4. In a certain population, 60% of adults prefer tea over coffee. A random sample of 8 adults is chosen.
(a) Find the probability that more than 5 adults prefer tea. [2]
(b) Find the expected number of adults who prefer tea in this sample. [1]
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5. The time taken by students to complete a statistics quiz is normally distributed with mean 25 minutes and variance 16 minutes2.
(a) Find the probability that a student takes between 20 and 30 minutes. [2]
(b) If 100 students take the quiz, estimate how many students take more than 33 minutes. [1]
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Section B: Sampling and Estimation (20 Marks)
6. A random sample of 10 students was asked how many hours they spent on social media last week. The results are summarized as follows:
∑x=120,∑x2=1550
(a) Calculate the unbiased estimate of the population mean. [1]
(b) Calculate the unbiased estimate of the population variance. [2]
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7. The masses of packets of rice are normally distributed with mean μ kg and standard deviation 0.05 kg. A random sample of 16 packets has a mean mass of 4.98 kg.
(a) Find a 95% confidence interval for the population mean μ. [3]
(b) State whether the population mean is likely to be 5.00 kg, giving a reason. [1]
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8. A surveyor wants to estimate the mean height of trees in a forest. He takes a random sample of 50 trees. The sample mean height is 12.5 m and the sample variance is 4.0 m2.
(a) Find the standard error of the mean. [2]
(b) Find the probability that the sample mean is within 0.5 m of the population mean. [3]
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9. The daily revenue of a shop is normally distributed with mean $2000 and standard deviation $300.
(a) Find the probability that the mean daily revenue over a period of 9 days is less than $1900. [3]
(b) Explain why the Central Limit Theorem is not needed in this calculation. [1]
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10. A manufacturer claims that the mean lifetime of their light bulbs is 1000 hours. A consumer group tests a random sample of 36 bulbs and finds a mean lifetime of 980 hours with a standard deviation of 60 hours.
(a) Calculate the test statistic for testing the manufacturer's claim. [2]
(b) State the distribution of the test statistic under the null hypothesis. [1]
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Section C: Hypothesis Testing and Regression (20 Marks)
11. A teacher claims that the mean score of her class in a test is greater than 70. A random sample of 25 students has a mean score of 74 and a standard deviation of 10. Assume the scores are normally distributed.
Test the teacher's claim at the 5% significance level.
(a) State the null and alternative hypotheses. [2]
(b) Calculate the test statistic. [2]
(c) Determine the critical value or p-value and state your conclusion in context. [3]
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12. The table below shows the advertising expenditure x (in $1000s) and sales y (in $10,000s) for 6 months.
| Month | x | y |
|---|
| 1 | 2 | 3 |
| 2 | 4 | 5 |
| 3 | 6 | 7 |
| 4 | 8 | 9 |
| 5 | 10 | 11 |
| 6 | 12 | 13 |
(a) Calculate the product moment correlation coefficient, r. [2]
(b) Interpret the value of r in the context of the data. [1]
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13. Using the data from Question 12:
(a) Find the equation of the regression line of y on x in the form y=a+bx. [2]
(b) Estimate the sales when the advertising expenditure is $15,000. [1]
(c) Comment on the reliability of this estimate. [1]
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14. A researcher investigates the relationship between study time (t hours) and exam marks (m). The regression line of m on t is found to be m=40+5t.
(a) Interpret the gradient of the regression line. [1]
(b) Explain why it might not be appropriate to use this line to predict the mark of a student who studied for 0 hours. [1]
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15. In a hypothesis test for the population mean, the null hypothesis is H0:μ=50 and the alternative hypothesis is H1:μ=50. The test is carried out at the 10% significance level.
(a) Define what is meant by the "critical region" in this context. [1]
(b) If the test statistic falls in the critical region, what conclusion should be drawn? [1]
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16. The number of customers entering a shop per hour follows a Poisson distribution with mean 8.
(a) Find the probability that exactly 6 customers enter in a given hour. [2]
(b) Find the probability that more than 10 customers enter in a given hour. [2]
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17. A box contains 5 red balls and 3 blue balls. Two balls are drawn at random without replacement.
(a) Draw a tree diagram to represent the outcomes. [2]
(b) Find the probability that both balls are red. [1]
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18. The heights of male students in a school are normally distributed with mean 170 cm and standard deviation 10 cm.
(a) Find the probability that a randomly selected student is taller than 185 cm. [2]
(b) Find the height h such that 90% of students are shorter than h. [2]
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19. A sample of 40 observations has ∑x=2000 and ∑x2=105000.
(a) Calculate the sample mean. [1]
(b) Calculate the unbiased estimate of the population variance. [2]
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20. The lifespan of a battery is normally distributed with mean 20 hours and standard deviation 2 hours.
(a) Find the probability that a battery lasts between 18 and 22 hours. [2]
(b) If 5 batteries are chosen at random, find the probability that all 5 last between 18 and 22 hours. [2]
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