Math Problem Statement

A student in the class is selected at random. Find the probability that the student has scored: (a) less than 20. (b) below 60 but 30 or more. (c) more than or equal to 70. (d) above 89.

Solution

The question provided asks to find the probability that a randomly selected student from a class of 100 students has scored within specific ranges.

Here is a summary of the dataThe question provided asks to find the probability that a randomly selected student from a class of 100 students has scored within specific ranges.

Here is a summary of the

Marks scoredNo. of students
0-104
10-205
20-309
30-407
40-5013
50-6012
60-7015
70-8011
80-9014
90-10010

Total number of students = 100.

Let's solve each option:

  1. Option (a): Probability that the student scored less than 20.

    • Number of students who scored in the range 0-20 (i.e., 0-10 and 10-20) = 4+5=94 + 5 = 9.
    • Probability = 9100=0.09\frac{9}{100} = 0.09.
  2. Option (b): Probability that the student scored below 60 but more than or equal to 30.

    • Number of students who scored between 30 and 60 (i.e., 30-40, 40-50, and 50-60) = 7+13+12=327 + 13 + 12 = 32.
    • Probability = 32100=0.32\frac{32}{100} = 0.32.
  3. Option (c): Probability that the student scored 70 or more.

    • Number of students who scored 70 or more (i.e., 70-80, 80-90, 90-100) = 11+14+10=3511 + 14 + 10 = 35.
    • Probability = 35100=0.35\frac{35}{100} = 0.35.
  4. Option (d): Probability that the student scored above 89.

    • Only students who scored in the 90-100 range satisfy this condition = 10 students.
    • Probability = 10100=0.10\frac{10}{100} = 0.10.

Answers:

  • (a) 0.090.09
  • (b) 0.320.32
  • (c) 0.350.35
  • (d) 0.100.10

Would you like more details or have any questions?

Here are 5 related questions to expand your understanding:

  1. What is the probability of selecting a student who scored between 40 and 80?
  2. If two students are selected at random, what is the probability that both scored less than 30?
  3. What is the probability of selecting a student who scored either below 40 or above 80?
  4. How does the total number of students affect the probabilities in such a distribution?
  5. Can you calculate the probability of selecting a student who scored between 50 and 100?

Tip: To calculate probability, divide the favorable outcomes by the total number of possible outcomes.

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Math Problem Analysis

Mathematical Concepts

Probability
Range of Scores
Data Distribution

Formulas

Probability = (Favorable outcomes) / (Total outcomes)

Theorems

Basic Probability Theorem

Suitable Grade Level

Grades 9-10