Tutor MathsGuru: Ask me for your burning Maths questions!

[jieheng]

wkong:

Hi,


Need help for the following:

Lily is meeting a friend at a certain time. If she drives at 80km/h, she will be 1/3hr late. If she drives at 60km/h, she will be 3/4hr late. How long will the journey take if she travelled at 90km/h?

Thanks,
wkong

Hi ,

Speed = Distance / Time taken

Time taken to complete the journey at 80 km/h : Time taken to complete
the journey at 60 km/h = 60 : 80 = 3 : 4

Difference in time taken = 3/4 h - 1/3 h
(4 - 3 ) unit = 9/12 h - 4/12 h
1 unit = 5/12 h

Time taken to complete the journey at 80 km/h = 3 units = 3 * 5/12 = 5/4 h

Distance between the journey = 5/4 * 80 = 100 km

Time taken to complete the journey at 90 km/h = 100 / 90 = 10/9 h = 1 1/9 h (Ans)

[wkong]

jieheng:

Hi ,


Speed = Distance / Time taken

Time taken to complete the journey at 80 km/h : Time taken to complete
the journey at 60 km/h = 60 : 80 = 3 : 4

Difference in time taken = 3/4 h - 1/3 h
(4 - 3 ) unit = 9/12 h - 4/12 h
1 unit = 5/12 h

Time taken to complete the journey at 80 km/h = 3 units = 3 * 5/12 = 5/4 h

Distance between the journey = 5/4 * 80 = 100 km

Time taken to complete the journey at 90 km/h = 100 / 90 = 10/9 h = 1 1/9 h (Ans)

Thank you

[jieheng]

Hi wkong ,


You are welcome .

[avell]

Dear all


Pls help me for the following questions:-

Qn (1)
4/5 of John’s money is equal to 3/8 of Sarah’s money. Express Sarah’s money as a ratio of John’s money in it simplest form (draw a model to help you to solve the sum.

Qn (2)
The ratio of boys and girls on a school bus was 2 : 3. When 16 girls alighted from the bus, the ratio of the remaining boys to girls became 6:5. Find the number of children who remained on the bus.

[wkong]

Hi All,


Need help for this question:

A train, 200m long, travelled through a tunnel at an average speed of 20m/s. The whole train took 2 min 30s to pass through the tunnel completely. Find the length of the tunnel in kilometres.

Thanks,
wkong

[rain29]

Hi Pixiedust,


Thanks for your help.

[jieheng]

wkong:

Hi All,


Need help for this question:

A train, 200m long, travelled through a tunnel at an average speed of 20m/s. The whole train took 2 min 30s to pass through the tunnel completely. Find the length of the tunnel in kilometres.

Thanks,
wkong

2 min 30 s = 150 s

Total distance travelled by the train = 20 * 150 = 3000 m

Length of tunnel = 3000 - 200 = 2800 m = 2.8 km (Ans)

[HVR]

Appreciate it if anyone can help. TIA


Roger is 30 yrs old when James is twice the age of John. When John is 21 yrs old, Roger is twice the age of James. Given that Roger is the oldest of them, find john’s age when Roger is 62 yrs old.

[jieheng]

HVR:

Appreciate it if anyone can help. TIA


Roger is 30 yrs old when James is twice the age of John. When John is 21 yrs old, Roger is twice the age of James. Given that Roger is the oldest of them, find john's age when Roger is 62 yrs old.

When Roger is 30 yrs old

Roger [ ][ ] [------] = 30 yrs
James [ ] [ ]
. John [ ]

[------] denotes the the difference of age between Roger and James and it will be the same throughout their lives

[ ] denotes the the difference of age between James and John and it will be the same throughout their lives . In this case , the ages of [ ]and[ ] are the same

When John is 21 yrs old

John [ 21 ]
James [ 21 ][ ]
Roger [ 21 ][ ][ 21 ][ ] as Roger is twice the age of James


[------] = [ 21 ][ ]


[ ][ ] [------] = 30 yrs

[ ][ ][ 21 ][ ] = 30 yrs

[ ] = [ ] = (30-21) / 3 = 3

When John is 3 yrs old , James is = 3 + 3 = 6 yrs old and Roger is 30 yrs old .

Roger is (30-3) = 27 yrs older than John .

When Roger is 62 yrs old ,

John is = (62-27) = 35 yrs old (Ans)

[wahwah]

HI,

Need help with the following math questions. Many thanks in advance.

A worker takes 9 hrs to build a wall while another worker takes 10 hr to build the same wall. When both workers work together, they sometimes stop for a chat and they lay 10 bricks fewer per hour than their total if they had worked seperately. If the two workers take 5 hours to build the wall together, how many bricks are needed for the wall?

I have six coins- three 5 cents coins and three 10 cents coins. I place two coins in each of three boxes labeled 10 cents, 15cents and 20cents in such a way that these are not the respective values of coins inside. What is the least number of coins you would have to remove, and from which box or boxes, so as to determine which coins are in which boxes? Write your explanation clearly.