Q90.Four persons can hit a target correctly with probabilities 1 2 , 13 , 14 and 18 respectively. If all hit at the target independently, then the probability that the target would be hit, is (1) 25 (2) 7 192 32 (3) 1 (4) 25 192 32 JEE Main 2019 (09 Apr Shift 1) JEE Main Previous Year Paper
What This Question Tests
This question is a straightforward application of probability for independent events, specifically finding the probability that at least one person hits the target using the concept of complementary events.
Concepts Tested
Formulas Used
P(A or B) = 1 - P(not A and not B)
P(A and B) = P(A)P(B) for independent events
📚 NCERT Sections This Tests
12.5 — A Hydrogen Atom Initially In The Ground Level Absorbs A Photon,
Physics Class 12 · Chapter 12
12.5 A hydrogen atom initially in the ground level absorbs a photon, which excites it to the n = 4 level. Determine the wavelength and frequency of photon.
9.17 — (A) Sin I¢C = 1.44/1.68 Which Gives I¢C = 59°. Total Internal Reflection
Physics Class 12 · Chapter 9
9.17 (a) sin i¢c = 1.44/1.68 which gives i¢c = 59°. Total internal reflection takes place when i > 59° or when r < rmax = 31°. Now, (sin i /sin r max max ) = 1.68 , which gives imax ~ 60°. Thus, all incident rays of angles in the range 0 < i < 60° will suffer total internal reflections in the pipe. (If the length of the pipe is finite, which it is in practice, there will be a lower limit on i determined by the ratio of the diameter to the length of the pipe.) (b) If there is no outer coating, i¢c = sin–1(1/1.68) = 36.5°. Now, i = 90° will have r = 36.5° and i¢ = 53.5° which is greater than i¢c. Thus, all incident rays (in the range 53.5° < i < 90°) will suffer total internal reflections.
11.6 — The Threshold Frequency For A Certain Metal Is 3.3 × 1014 Hz. If Light
Physics Class 12 · Chapter 11
11.6 The threshold frequency for a certain metal is 3.3 × 1014 Hz. If light of frequency 8.2 × 1014 Hz is incident on the metal, predict the cut- off voltage for the photoelectric emission.
📋 Question Details
- Chapter
- Probability
- Topic
- Probability of independent events
- Year
- 2019
- Shift
- 09 Apr Shift 1
- Q Number
- Q90
- Type
- MCQ
- NCERT Ref
- Class 12 Mathematics Ch 13: Probability
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