If from each of the three boxes containing 3 white and 1 black, 2 white and 2
black, 1 white and 3 black balls, one ball is drawn at random, then the probability
that 2 white and 1 black balls will be drawn is:
Given two unit vectors →a and →b, and the vectors →a+2→b and 5→a−4→b are perpendicular, we use the condition for perpendicular vectors:
(→a+2→b)⋅(5→a−4→b)=0
Expanding the dot product:
(→a+2→b)⋅(5→a−4→b)=→a⋅5→a+→a⋅(−4→b)+2→b⋅5→a+2→b⋅(−4→b)
Using properties of dot products and knowing →a and →b are unit vectors (→a⋅→a=1 and →b⋅→b=1):
5(→a⋅→a)−4(→a⋅→b)+10(→b⋅→a)−8(→b⋅→b)=0
Simplifying:
5(1)−4(→a⋅→b)+10(→a⋅→b)−8(1)=05−8+6(→a⋅→b)=0−3+6(→a⋅→b)=06(→a⋅→b)=3→a⋅→b=12
The dot product →a⋅→b=cosθ, where θ is the angle between →a and →b:
cosθ=12
Therefore, the angle θ is:
θ=cos−1(12)=60∘ Final Answer: 60∘
From (→a×→c)+→b=0, we get:
→a×→c=−→b
Let →c=xˆi+yˆj+zˆk.
The cross product →a×→c is:
→a×→c=|ˆiˆjˆk1−10xyz|
Expanding this determinant:
→a×→c=(zˆi+zˆj+(x+y)ˆk)
Setting →a×→c=−→b, we get:
z=−1,z=−1,x+y=−1
Therefore:
x+y=−1
Now, from →a⋅→c=4:
→a⋅→c=1⋅x+(−1)⋅y=4
Simplifying:
x−y=4
Solving the system of equations:
x+y=−1x−y=4
Adding the two equations:
2x=3⇒x=32
Substituting into x+y=−1:
32+y=−1⇒y=−52
Now, →c=32ˆi−52ˆj−ˆk.
To find |→c|2, we compute:
|→c|2=(32)2+(−52)2+(−1)2=94+254+1|→c|2=9+25+44=384=9.5 Final Answer: 9.5
A spring is being moved up and down. An object is attached to the end of the
spring that undergoes a vertical displacement. The displacement is given by the
equation y=3.50sint+1.20sin2t. Find the first two values of t (in seconds) for
which y =0.
A ball is thrown off the edge of a building at an angle of 60° and with an initial
velocity of 5 meters per second. The equation that represents the horizontal
distance of the ball x is x=ν0(cosθ)t, where ν0 is the initial velocity. θ is the
angle at which it is thrown and t is the time in seconds. About how far will the ball
travel in 10 seconds?
The a, b, c and d are in GP and are in ascending order such that a+d = 112 and b+c 48. If the GP is continued with a as the first term, then the sum of the first six
terms is:
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : In a class of 40 students. 22 drink Sprite, 10 drink Sprite but not Pepsi. Then the number of students who drink both Sprite and Pepsi is 15.
Reason R: For any two finite sets A and B, n(A)=n(A−B)+n(A∪B)
In the light of the above statements, choose the most appropriate answer from the options given below:
There are 200 students in a school out which 120 students play football, 50 students play cricket and 30
students play both football and cricket. The number of students who play one game only is:
There are 15 points in a plane such that 5 points are collinear and no three of the remaining points are collinear
then total number of straight lines formed are:
An equilateral triangle is inscribed in a parabola y2=8x whose one vertix is at the vertex of the parabola then the length of the side of the triangle is:
If the parametric equation of a curve is given by x=etcost and y=etsint then the tangent to the curve at the point t=π4 makes the angle with the axis of x is
x=etcost,y=etsint
To find the angle of the tangent at t=π4, compute the slope: dydx=dydtdxdt=et(sint+cost)et(cost−sint)=sint+costcost−sint
At t=π4, sin(π4)=cos(π4)=√22
So,
dydx=√22+√22√22−√22=√20
The slope is undefined, which means the tangent is vertical.
(A) If each element in a row is a constant multiplier of corresponding element of another row of a determinant, then the value of the determinant is always non-zero.
(B) If each element on one side of the principal diagonal of a determinant is zero, then the value of the determinants the product of the diagonal elements.
(C) The value of determinant of skew symmetric matrix of odd order is always non-zero.
(D) If A is non-singular matrix of order three, then adj A=|A|^2
Choose the correct answer from the options given below:
A function f(x) is defined as f(x)=\begin{cases}{\frac{1-\cos 4x}{{x}^2}} & {;x{\lt}0} \\ {a} & {;x=0} \\ {\frac{\sqrt[]{x}}{\sqrt[]{(16+\sqrt[]{x})-4}}} & {;x{\gt}0}\end{cases}
if the function f(x) is continuous at x = 0, then the value of a is:
Let \alpha >2 is an integer. If there are only 10 positive integers satisfying the inequality (x-\alpha)(x-2\alpha)(x-\alpha^2)<0 then the value/s of \alpha is
The arithmetic mean and standard deviation of series of 20 items were calculated
by a student as 20 cm and 5 cm respectively. But while calculating them an item
15 was misread as 30. Find the correct standard deviation.
Given the marks of 25 students in the class as \{m_1,m_2,m_3,..m_{25}\}. Marks lie in the
range of [1-100] and \overline{m} is the mean. Which of the following quantity has the value
zero?
Consider n events {{E}}_1,{{E}}_2\ldots{{E}}_n with respective probabilities {{p}}_1,{{p}}_2\ldots{{p}}_n. If P\Bigg{(}{{E}}_1,{{E}}_2\ldots{{E}}_n\Bigg{)}=\prod ^n_{i=1}{{p}}_i, then
Total people = 4 Indians + 3 Americans + 2 Britishers = 9
Since arrangement is around a circular table, we fix one position ⇒ remaining to arrange: 8 positions
Group the 3 Americans together as a single unit ⇒ total units = 4 Indians + 1 American group + 2 Britishers = 7 units
Circular arrangement of 7 units = (7 - 1)! = 6!
Given three identical boxes B1 B2 and B3 each containing two balls. B1 containstwo golden balls. B2 contains two silver balls and B3 contains one silver and onegolden ball. Conditional probabilities that the golden ball is drawn from B1, B2, B3are ____,______,______ respectively