P6 Maths Qn

Chocolate Cake SG

Got this qn from another blog and so far nobody has answered since it was posted on 10 Dec 2008. Pls kindly spare your time & try to answer it.

A 6-sided dice with equal chances has the numbers 1, 2, 3, 4. 5 and 6 written on its faces. The dice is tossed twice and the numbers obtained are recorded accordingly. What is the maximum number of ways for the sum of the two recorded numbers to be a number that has 2 factors only?

BTW, this is my first posting in this forum & I find it helpful with many nice ppl around.

Cheers.

jayh272416 SG

possible answers are 2 3 4 5 6 7 8 9 10 11 12

2 factos = prime number

primes are 2 3 5 7 11

so its 5 ways.

*edit*

unless you mean that, for example, 6 and 5, and 5 and 6 are different though the sum is the same,

2 has one way (1 1)
3 has 2 ways
5 has 4 ways
7 has 6 ways
11 has 2 ways

so it means it is 15 ways.

Chocolate Cake SG

Yes, got the reply from the person that had posted this qn. Answer is 15 ways.
Thanks for your super fast & detailed explanation.

Cheers.

syncopation_music SG

hi ..i need to understand how to explain the answer to a P6 student.so its easy to learn .its by a famous maths author..and no worked solution at all ...zzz

hope anyone can help me with this ..answers i have to get the book then check

all help deeply appreciated ;)

Mr Lim bought a total of 75 apples and oranges.After 1/3 of the apples and
3/4 of the oranges were eaten ,a total of 25 apples and oranges were left.
How many apples did Mr Lim buy?

Tap A can fill an empty tank in 15min.Tap B can empty a similar tank that
is completely filled in 12 mins .Both taps are turned on at the same time when 3/4 of the tank is filled with water.How long will it take for the tank to be completely emptied ?

[Please ignore the dimension of the tank ..no dimension is given in the REAL QUESTION ]

this is just a generic pic of Tap A[top one] and Tap B[the draining tap]

At a stall , there are some buns and cakes .If 20 buns and 60 cakes are sold per minute ,there will be 80 cakes left when all the buns are sold .
If 60 buns and 20 cakes are sold per minute ,there will be 400 cakes left and when all the buns are sold.How many buns are there at stall ?

jayh272416 SG

Mr Lim bought a total of 75 apples and oranges.After 1/3 of the apples and
3/4 of the oranges were eaten ,a total of 25 apples and oranges were left.
How many apples did Mr Lim buy?

use algebra

A+O=75
(2/3)A+(1/4)O=25
therefore 8/3A+O=100
5/3A=25
number of apples = 25 x 3/5 = 15
number of oranges = 75-15 = 60

jayh272416 SG

[Please ignore the dimension of the tank ..no dimension is given in the REAL QUESTION ]

this is just a generic pic of Tap A[top one] and Tap B[the draining tap]

Convert to 1 min

in 1 min 1/15 of the tank is filled up and 1/12 of the tank is emptied

therefore in 1 min, the change in volume is 1/15-1/12

= 4/60-5/60
= -1/60

thus 1/60 of the tank is emptied in 1 min

time taken to empty 3/4 of the tank is (3/4)/(1/60)

= 45 min

Daisuke-kun SG

wah!

pri6 learn dis liao?

shocking

jayh272416 SG

let m be the time taken to sell all the buns using scenario 1
let n be the time taken to sell all the buns using scenario 2

therefore
20m = 60n
60m+80=20n+400

divide both equations by 20

m=3n
3m+4=n+20

take 3 times of the first eqn

3m = 9n
sub into 2nd eqn
9n+4=n+20
8n=16
n=2

thus number of buns sold is 60n=120

jayh272416 SG

wah!

pri6 learn dis liao?

shocking

pri 6 learn algebra woh.

d3sT1nY SG

I though primary school still using the bar model kind of thing. Can use algebra meh? Don't play cheat leh. Haha.

SBS261P SG

the bun one can have creative method of solving

if i sell 20 bun and 60 cake per minute i will have 80 cake left

this means that

if i sell 60 bun and 180 cake per 3 minutes, i will have 80 cake left

if i sell 60 bun and 20 cake per 1 minute, i will have 400 cake left.

so for every 60 bun i sell, for the first one i sell 180 cake, second one i sell 20 cake

the difference in cake i sell is 160 cake.

i got 400 – 80 = 320 more cakes if i sell slower

320 / 160 = 2

means that i sell 2 sets of 60 bun = 120 bun

i think this easier for primary school to learn? or maybe because i lao jiao so i think this one very simple but primary student think very hard? not sure

syncopation_music SG

hi this two question is tough .. i would need some help to explain to my student

hope any kind soul help out there

baiyun SG

Hope it helps.

syncopation_music SG

A cylindrical drum is being filled with petrol flowing from a tap. The volume of petrol in the drum ,V litres , after x minutes is given by V=20+4x litres .Find the volume of petrol in the drum after 38 minutes .

when i look at the answer , i coudnt figure out the answer for this is 80 litres .

any person who want to try ?

d3sT1nY SG

when i look at the answer , i coudnt figure out the answer for this is 80 litres .

any person who want to try ?

The answer sheet is wrong.

787180 SG

How to do this in a simpler manner?

Kit and Roy are given some money.If Kit and Roy spend $50 and $25 respectively each day,Kit will still have $600 when Roy has spent all his money.If Kit and Roy spend $25 and $50 respectively,Kit will still have $1800 when Roy has spent all his money.How much money is given to each boy?

Only-Way-4-Destiny! SG

All relax ok? Its just P6 maths qn

Amktsy SG

i think the answer is 11.

not sure correct or not but i did pass my maths for psle although not really good.

dlocenot SG

K-2R=600

K-0.5R=1800

Solving, Kit=2200, Roy=800

syncopation_music SG

Hi all , just want to know where i gone wrong

i have been trying but i just dont seems to get the answer which is $120

The question as below :

A clock costs five times as much as a lamp .If the lamp costs $80 less than the clock ,Find the total cost of the clock and the lamp

much appreciated for any help

thanks