# Mathematics: Post your doubts here!

#### chishtyguy

Help!
In how many ways can 13 cards in a pack of 52 cards be arranged?
52P13

#### chishtyguy

shldnt combination be used here? as well as permutation ofc
no. all cards are different and they are to be arranged and not chosen.

#### RoOkaYya G

no. all cards are different and they are to be arranged and not chosen.
owwkay .-.
ty

#### Lostsoul

Help:
If the letters of the word 'MINIMUM' are arranged in a line at random. What is the probability that the arrangement begins with MMM?

#### Lostsoul

Again:
In how many ways can 10 students be arranged in a way that 2 youngest are separated?

#### Lostsoul

I. How many 4 digit numbers can be formed from the digits 1,2,3 and 5 If repetitions are not allowed?

II. How many 4 digit numbers divisible by 5 can be formed from the digits above?

#### Keirad

I. How many 4 digit numbers can be formed from the digits 1,2,3 and 5 If repetitions are not allowed?

II. How many 4 digit numbers divisible by 5 can be formed from the digits above?

I- 4!
II- 3!

#### Lostsoul

I- 4!

Thanks
For part II you take it as non repeating again?

Why not 3! +/× 2! ?

Thanks in advance

#### Keirad

For II
Sorry...my mistake
If it can be repeated then it will be 4^3

#### Snowysangel

find normal (n hat) by doing cross product with the direction of line l and the directon vector A.

replace in the formula r. n hat = a . n hat

a can be the point in line equation (4,-2,2)

replace n u get the answer.
That's the normal to the plane right? How do you find it?

#### RoOkaYya G

That's the normal to the plane right? How do you find it?
cross product of direction of line n direction vector A
i mentioned it there

#### Snowysangel

cross product of direction of line n direction vector A
i mentioned it there
Yeah what's the general equation for it? Is it the cross product of the position vector of any point on a plane and the direction vector? Isn't the direction of line l the same as the direction vector A?

#### Lily9605

Hi..could someone tell me how to do qn 2?

#### Attachments

• 9709_s14_qp_73.pdf
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#### ahmed butt

can anyone tell me how to study math as level pure math and stats 1

#### RoOkaYya G

can anyone tell me how to study math as level pure math and stats 1
practice papers a lot.

#### Thought blocker

can anyone tell me how to study math as level pure math and stats 1
Understanding concepts and applying them into exercise and papers is the way. All the best.

#### TimBluesWin

Hey everyone....

How's your statistics's exam? I'm taking variant 2 btw....

#### Thought blocker

TimBluesWin Paper has been successfully uploaded with the worked solutions. Check out my signature.

#### Salman Shah Jee

When it says , Find all the roots in the interval (-180 < x <180) of the following equations : 1) 4 sin X = 5 cosX 2) cos3X =2/3
Now what is the difference between cos3X and 3cos X? Are they both same? . And which roots lie in the interval ( -180 < x < 180)??????...What does -180 means? Plzzz solve both question step by step.Thanks