Homework Help Plz

[monkey_henry]

I hope that this is in the right forum, but I need help on some math homework.
Ok, here are the questions:
1)The sum of seven consecutive positive integers is always
A) odd B) a multiple of 7 C) even D) a multiple of 4 E) a multiple of 3
I think its B but im not sure.

2) Kalyn writes down all of the integers from 1 to 1000 that have 4 as the sum of their digits. If a/b (in lowest terms) is the fraction of these numbers that are prime, then a+b is
A)5 B)4 C)15 D) 26 E)19
I have no idea about this one.

3) Four identical isosceles triangles border a square of side 6 cm. When the four triangles are folded up they meet at a point to form a pyramid with a square base. If the height of this pyramid is 4 cm, the total area of the four triangles and the square is
A) 84 cm squared B) 98 cm squared C) 96 cm squared D) 108 cm squared E) 90 cm squared
I think it is D but again im not sure.

Plz post or pm me if u can help or give me the answer thanx!

[thorax_the_basher]

Re: Homework Help Plz

what math are you in?, just woundering cuz im in 11th grade and dont think ive ever learned anything about that. sorry i cant be much more help but will ask my mom/ dad when they get home and see if they have any idea. Thak ok with you?

[monkey_henry]

Re: Homework Help Plz

No prob thanx for for helping.
Get back to me if u find the answer.
BTW im in grade eight

[dancingmaniac3]

Re: Homework Help Plz

for number 1, write down seven consecutive numbers and see. Its easier than it looks, it really is.

ex:

1+2+3+4+5+6+7 = 28

28 = a multiple of 7, 4, and is even.

so that counts out A and E.

so try a new seven numbers:

2+3+4+5+6+7+8 = 35

35 = odd, so that counts out C.
35 = multiple of 7, so that leaves B.
35 = not a multiple of 4, counting out D. Leaving you with choice B. A multiple of 7. yay.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Reach]

Re: Homework Help Plz

#1.

B

#2. There are 15 of them.

1/3 of them are prime, so the answer is B

#3. The answer is A. 36+48 = 84

[Shashakiro]

Re: Homework Help Plz

uhh yeah 1 is B but I have no idea how what Reach posted has anything to do with the question =P

P.S. #3 is A.

4 cm altitude * 4 triangles * 6 base / 2 = 48
6^2 = 36

add to get 84

[Reach]

Re: Homework Help Plz

I thought the consecutive ment that it was repeating. I guess it doesn't matter, the answer is the same xD

Oh and the answer is 84 to the last one. I thought it ment the area inside, oops.

[Shashakiro]

Re: Homework Help Plz

The volume would have been 36 by the way, if that was the question =P

[monkey_henry]

Re: Homework Help Plz

uhh yeah 1 is B but I have no idea how what Reach posted has anything to do with the question =P

P.S. #3 is A.

4 cm altitude * 4 triangles * 6 base / 2 = 48
6^2 = 36

add to get 84

Thats what i thought too but i though that seemed too easy.
i dont think that the altitude is 4 cm though. because i dont think the height of the pyramid is the altitude of the triangles though.
EDIT and my friend said something about the altitudes of the triangles being 6 cm.

[thorax_the_basher]

Re: Homework Help Plz

#2 is B like they said because there are 15 total, 5 are prime, so thats 1/3 in terms of a and b, so a+b=4

[monkey_henry]

Re: Homework Help Plz

yeah i know the equations just not sure of the answer.

[Shashakiro]

Re: Homework Help Plz

Oh nvm. Silly mistake. ><

#3 is 96, so C. We were all wrong before XD

P.S. #3 is an awfully hard problem for 8th grade o.O

[monkey_henry]

Re: Homework Help Plz

can you explain how? and yes i know this is hard for 8th grade thats y i needed help. the first one i wanted to confirm my answer and i didnt understand the second one.

[Reach]

Re: Homework Help Plz

Oh nvm. Silly mistake. ><

#3 is 96, so C. We were all wrong before XD

P.S. #3 is an awfully hard problem for 8th grade o.O

Sneaky question.

Owned by rushing through grade 8 math. arg.

[monkey_henry]

Re: Homework Help Plz

lol im pretty sure this isnt 8th grade material i think this is just a bonus question.