Practice Questions

Q89.A person throws two fair dice. He wins Rs. 15 for throwing a doublet (same numbers on the two dice), wins Rs 12 when the throw results in the sum of 9 , and loses Rs. 6 for any other outcome on the throw. Then the expected gain/loss (in Rs.) of the person is: (1) 1 loss (2) 1 gain 2 2 (3) 2 gain (4) 1 loss 4

Q89.Let S = {1, 2, … . . , 20}. A subset B of S is said to be "nice", if the sum of the elements of B is 203 . Than the probability that a randomly chosen subset of S is "nice" is : JEE Main 2019 (11 Jan Shift 2) JEE Main Previous Year Paper (1) 7 (2) 5 220 220 (3) 4 (4) None of the above 220

Q89.The plane passing through the point (4, −1, 2) and parallel to the lines x+23 = y−2−1 = z+12 and x−2 1 = y−32 = z−43 also passes through the point (1) (1, 1, −1) (2) (−1, − 1, −1) (3) (−1, −1, 1) (4) (1, 1, 1)

Q89.The equation of the plane containing the straight line x 2 = 3y = 4z and perpendicular to the plane containing the straight lines x 3 = 4y = 2z and x4 = 2y = 3z is: (1) 3x + 2y −3z = 0 (2) x + 2y −2z = 0 (3) x −2y + z = 0 (4) 5x + 2y −4z = 0

Q89.If the line 𝑥- 2 = 𝑦+ 1 = 𝑧- 1 intersects the plane 2𝑥+ 3𝑦- 𝑧+ 13 = 0 at a point 𝑃 and the plane 3 2 -1 3𝑥+ 𝑦+ 4𝑧= 16 at a point 𝑄, then 𝑃𝑄 is equal to JEE Main 2019 (12 Apr Shift 1) JEE Main Previous Year Paper (1) 2√7 (2) 14 (3) 2√14 (4) √14

Q89.If Q(0, −1, −3) is the image of the point P in the plane 3x −y + 4z = 2 and R is the point (3, −1, −2), then the area (in sq. units) of ΔPQR is (1) √91 (2) √91 4 2 (3) 2√13 (4) √65 2 JEE Main 2019 (10 Apr Shift 1) JEE Main Previous Year Paper

Q90.Let 𝐴 and 𝐵 be two non-null events such that 𝐴⊂𝐵. Then, which of the following statements is always correct? (1) 𝑃𝐴| 𝐵≥𝑃( 𝐴) (2) 𝑃𝐴| 𝐵= 𝑃𝐵- 𝑃𝐴 (3) 𝑃𝐴| 𝐵≤ 𝑃( 𝐴) (4) 𝑃𝐴| 𝐵= 1 JEE Main 2019 (08 Apr Shift 1) JEE Main Previous Year Paper

Q90.A bag contains 30 white balls and 10 red balls. 16 balls are drawn one by one randomly from the bag with replacement. If X be the number of white balls drawn, then ( standardmeandeviationof X of X ) is equal to: (1) 4 (2) 4√3 (3) 3√2 (4) 4√3 3 JEE Main 2019 (11 Jan Shift 2) JEE Main Previous Year Paper

Q90.Two integers are selected at random from the set {1, 2, … , 11} . Given that the sum of selected numbers is even, the conditional probability that both the numbers are even is : (1) 7 (2) 1 10 2 (3) 2 (4) 3 5 5 JEE Main 2019 (11 Jan Shift 1) JEE Main Previous Year Paper

Q90.If the probability of hitting a target by a shooter, in any shot is 1 3 , then the minimum number of independent shots at the target required by him so that the probability of hitting the target at least once is greater than 5 6 , is: (1) 4 (2) 5 (3) 6 (4) 3 JEE Main 2019 (10 Jan Shift 2) JEE Main Previous Year Paper

Q90.Minimum number of times a fair coin must be tossed so that the probability of getting at least one head is more than 99% is: (1) 8 (2) 6 (3) 5 (4) 7 JEE Main 2019 (10 Apr Shift 2) JEE Main Previous Year Paper

Q90.In a random experiment, a fair die is rolled until two fours are obtained in succession. The probability that the experiment will end in the fifth throw of the die is equal to : (1) 150 (2) 175 65 65 (3) 225 (4) 200 65 65 JEE Main 2019 (12 Jan Shift 1) JEE Main Previous Year Paper

Q90.Two newspapers A and B are published in a city. It is known that 25% of the city population reads A and 20% reads B while 8% reads both A and B. Further, 30% of those who read A but not B look into advertisements and 40% of those who read B but not A also look into advertisements, while 50% of those who read both A and B look into advertisements. Then the percentage of the population who look into advertisements is: (1) 13.5 (2) 12.8 (3) 13.9 (4) 13 JEE Main 2019 (09 Apr Shift 2) JEE Main Previous Year Paper

Q90.An urn contains 5 red and 2 green balls. A ball is drawn at random from the urn. If the drawn ball is green, then a red ball is added to the urn and if the drawn ball is red, then a green ball is added to the urn; the original ball is not returned to the urn. Now, a second ball is drawn at random from it. The probability that the second ball is red, is: (1) 21 (2) 26 49 49 (3) 32 (4) 27 49 49 JEE Main 2019 (09 Jan Shift 2) JEE Main Previous Year Paper

Q90.Assume that each born child is equally likely to be a boy or girl. If two families have two children each, then the conditional probability that all children are girls given that at least two are girls is: (1) 1 (2) 1 12 10 (3) 1 (4) 1 11 17 JEE Main 2019 (10 Apr Shift 1) JEE Main Previous Year Paper

Q90.The minimum number of times one has to toss a fair coin so that the probability of observing at least one head is at least 90% is: (1) 2 (2) 4 (3) 5 (4) 3 JEE Main 2019 (08 Apr Shift 2) JEE Main Previous Year Paper

Q90.Two cards are drawn successively with replacement from a well-shuffled deck of 52 cards. Let 𝑋 denote the random variable of number of aces obtained in the two drawn cards. Then 𝑃𝑋= 1 + 𝑃𝑋= 2 equals: 24 52 (1) (2) 169 169 49 25 (3) (4) 169 169 JEE Main 2019 (09 Jan Shift 1) JEE Main Previous Year Paper

Q90.An unbiased coin is tossed. If the outcome is a head then a pair of unbiased dice is rolled and the sum of the numbers obtained on them is noted. If the toss of the coin results in tail then a card from a well-shuffled pack of nine cards numbered 1, 2, 3, … , 9 is randomly picked and the number on the card is noted. The probability that the noted number is either 7 or 8 is (1) 13 (2) 19 36 72 (3) 15 (4) 19 72 36 JEE Main 2019 (10 Jan Shift 1) JEE Main Previous Year Paper

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

Q90.Let a random variable 𝑋 has a binomial distribution with mean 8 and variance 4. If 𝑃𝑋≤2 = 𝑘 then the 216, value of 𝑘 is equal to (1) 121 (2) 1 (3) 17 (4) 137 JEE Main 2019 (12 Apr Shift 1) JEE Main Previous Year Paper

Q90.For an initial screening of an admission test, a candidate is given fifty problems to solve. If the probability that the candidate can solve any problem is 4 5 , then the probability that he is unable to solve less than two problems is (1) 201 5 ( 51 ) 49 (2) 16425 ( 51 ) 48 (3) 316 25 ( 54 ) 48 (4) 545 ( 54 ) 49 JEE Main 2019 (12 Apr Shift 2) JEE Main Previous Year Paper

Q90.In a game, a man wins Rs. 100 if he gets 5 or 6 on a throw of a fair die and loses Rs. 50 for getting any other number on the die. If he decides to throw the die either till he gets a five or a six or to a maximum of three throws, then his expected gain/loss (in rupees) is : (1) 400 gain (2) 400 gain 3 9 (3) 400 loss (4) 0 3 JEE Main 2019 (12 Jan Shift 2) JEE Main Previous Year Paper

Q1. The characteristic distance at which quantum gravitational effects are significant, the Planck length, can be determined from a suitable combination of the fundamental physical constants G, h and c. Which of the following correctly gives the Planck length? (1) G2hc (2) Gh 21 ( c3 ) (3) G 12 h2c (4) G (h2c3

Q1. Let A = + and B = − . The magnitude of a coplanar vector C such that (ˆi ˆj) (2ˆi ˆj) → → → → → → A . C = B. C = A . B is given by: (1) √912 (2) √209 (3) √59 (4) √109

Q1. The density of a material, in the shape of a cube, is determined by measuring three sides of the cube and its mass. If the relative errors in measuring the mass and length are 1. 5% and 1%, respectively, the maximum error in determining the density is: (1) 6 % (2) 2.5 % (3) 3.5 % (4) 4.5 %