Q&A - P5 Math

[tianzhu]

veraclari:

Hi all thanks to the sharing s here I know ratio must use cross multiply method sometimes. However can u kindly share how we determine what to cross multiply or the factor to multiply as I'm confused...Eg. In the qquestion and model answer attached, why X 6 & X 7? How to dderive 6&7? TIA!


Qn: ratio of no. Of girl to boy is 6:5. No. Of girl swimmers to girl non swimmers is 5:2. Ratio of boy swimmers to boy non swimmers is 3:2.
A) what fraction of children is non swimmers?
B) if there were 30 more boys non swimmers than girl non swimmers. How many swimmers were there altogether?
Model Answer

'''''''' 5 : 2 ---------3 : 2
((X6)) 30 : 12 ---------21 : 14 ((X7))
A) total units -> 42+35= 77
Total non swimmers -> 12+14 = 26

Kindly advise why they multiply by 6&7? How to get 6&7 in e first place?

Hi

Good Morning

First thing first, I am just wondering if you copied this question word by word from the book or just summarised the question.

Students will be able to solve such questions with equivalent ratios.

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8524/8619895599_38361ee2e0_z.jpg\">

[tianzhu]

Hi moderators


Please help to delete.

I’ve revised the post.

Best wishes.

[tianzhu]

Hi moderators


Please help to delete.

This post is superseded by the blog.

Best wishes.

[chloecube]

needed help on this 2,thks


the number of marble lenny has is 1 less than 4 times that of Ryan’s. the number of marble that sam has is 6 more than 1/11 of lenny. sam has 10 fewer marble than ryan. how many marble do they have altogether?

tom spent 7/9 of his money on 6 chicken burger, 16 hamburger and 12 nuggets. he could spent all the remaining money on 4 chicken burger and 8 nugget, but changed his mind to spend it on hamburger only.
a) how many hamburger did tom buy with the remaining money?
b) if tom has $45, how much did each hamburger cost?

[tianzhu]

chloecube:

needed help on this 2,thks

the number of marble lenny has is 1 less than 4 times that of Ryan's. the number of marble that sam has is 6 more than 1/11 of lenny. sam has 10 fewer marble than ryan. how many marble do they have altogether?

Hi

A neat way is to use MD or you may use units.

Draw 1 box + 6 to show Sam.

Draw 11 boxes to show Lenny.

Ryan’s share ------- 1 box + 6 + 10 (Sam has 10 fewer marble than Ryan.)

11 boxes + 1 ------- 4 boxes + 64 (The number of marble Lenny has is 1 less than 4 times that of Ryan's.)

7 boxes ------ 63

1 box ------- 9

Please continue from here.

The answer is 139.

Best wishes

[PapayaDad]

tom spent 7/9 of his money on 6 chicken burger, 16 hamburger and 12 nuggets. he could spent all the remaining money on 4 chicken burger and 8 nugget, but changed his mind to spend it on hamburger only.

a) how many hamburger did tom buy with the remaining money?
b) if tom has $45, how much did each hamburger cost?

7u=6c+16h+12n

2u=4c+8n
1u=2c+4n
7u=14c+28n

since 7u = 7u ; so

6c+16h+12n = 14c+28n
16h = 8c + 16n (this is actually = 4u)
16h = 4u
2u = 8h ; can buy 8 hamburger with the remaining money

if he have $45; his remaining is 2/9 = $10 can buy 8 hamburger
each hamburger cost 10/8 = $1.25

[chloecube]

Thank you so much!!

[chloecube]

1001 card were given to 49 children. 3/7 were girls.each boy received the same number of cards. each girl received thrice as much as each boy.how many more card did the all girls received as all the boys?


is the answer 385?

[tianzhu]

chloecube:

1001 card were given to 49 children. 3/7 were girls.each boy received the same number of cards. each girl received thrice as much as each boy.how many more card did the all girls received as all the boys?


is the answer 385?

Hi

Please check your source because you'll end up with decimals.You are more likely to be given a card in a whole piece rather than partially.

Best wishes

[chloecube]

tianzhu:

chloecube:

needed help on this 2,thks

the number of marble lenny has is 1 less than 4 times that of Ryan's. the number of marble that sam has is 6 more than 1/11 of lenny. sam has 10 fewer marble than ryan. how many marble do they have altogether?

Hi

A neat way is to use MD or you may use units.

Draw 1 box + 6 to show Sam.

Draw 11 boxes to show Lenny.

Ryan’s share ------- 1 box + 6 + 10 (Sam has 10 fewer marble than Ryan.)

11 boxes + 1 ------- 4 boxes + 64 (The number of marble Lenny has is 1 less than 4 times that of Ryan's.)

7 boxes ------ 63

1 box ------- 9

Please continue from here.

The answer is 139.

Best wishes

hi tianzhu

went home sit down to look through the answer
i do not understand this part,
11 boxes + 1 ------- 4 boxes + 64 (The number of marble Lenny has is 1 less than 4 times that of Ryan's.)

since Lenny has 1 less than 4 times of Ryan, why his his 11 boxes +1? shldnt it be -1 instead?

in fact i do not quite comprehen the first sentence of this sum.
the number of marble lenny has is 1 less than 4 times that of Ryan's.

thks so much for helping