O-Level Additional Math

[chrisu]

A Sec.2 Maths question of Proportion.


Q) The scale of map P is 1:p and the scale of map Q is 1:q. If the same area is represented as 32sq.cm. on map P and 50sq.cm. on map Q, calculate the ratio p:q.

Kindly show workings as well.

Thank you.

[ChubbyMama]

Please Help :


Find the greatest number that will divide 171, 255 and 304 so as to leave the same remainder in each case.

Thank you in advance

[chrisu]

Please help A Sec.2 Maths question of Proportion.


Q) The scale of map P is 1:p and the scale of map Q is 1:q. If the same area is represented as 32sq.cm. on map P and 50sq.cm. on map Q, calculate the ratio p:q.

Kindly show workings as well.

Thank you.

[TheOliveTree]

Hi chrisu,


Determine the scale for area first from the given linear scale.

Map P
1 cm : p cm
1 cm^2 : p^2 cm^2
32 cm^2 : 32p^2 cm^2

Map Q
1 cm : q cm
1 cm^2: q^2 cm^2
50 cm^2 : 50q^2 cm^2

Since the actual areas represented on Map P and Map Q are the same,

50q^2=32p^2
p^2/q^2=32/50
p/q = sqrt (32/50)
p/q= 8/10 = 4/5

Ratio of p:q = 4:5

Hope this helps.

The Olive Tree Learning Hub

[YumYum]

Hi, need help with this sec1 Qn:


The key to a code is given by three whole numbers. The key is transmitted from the headquarters by 3 agents, who were given the product of 2 of the 3 numbers. Suppose that the numbers transmitted are 432, 540 and 720. What is the key code?

thanks.

[YumYum]

Hi, 1 more Qn:


Given that S =. 1
___________________________________________________
1/21 + 1/22 + 1/23 + 1/24 + 1/25 + 1/26 +…1/30

Find the largest whole number smaller than S.

Thanks

[chrisu]

Thank you very much TheOliveTree, especially the detailed workings.


Now I know how to explain to my daughter. But I think there is a slight mistake;
50q^2=32p^2
p^2/q^2=50/32 instead of 32/50.
Thus p/q = 5/4
The answer p:q = 5:4

Thanks once again.

TheOliveTree:

Hi chrisu,

Determine the scale for area first from the given linear scale.

Map P
1 cm : p cm
1 cm^2 : p^2 cm^2
32 cm^2 : 32p^2 cm^2

Map Q
1 cm : q cm
1 cm^2: q^2 cm^2
50 cm^2 : 50q^2 cm^2

Since the actual areas represented on Map P and Map Q are the same,

50q^2=32p^2
p^2/q^2=32/50
p/q = sqrt (32/50)
p/q= 8/10 = 4/5

Ratio of p:q = 4:5

Hope this helps.

The Olive Tree Learning Hub

[chrisu]

Can ignore this, I already got the workings and answer. Thank you.

chrisu:

Please help A Sec.2 Maths question of Proportion.

Q) The scale of map P is 1:p and the scale of map Q is 1:q. If the same area is represented as 32sq.cm. on map P and 50sq.cm. on map Q, calculate the ratio p:q.

Kindly show workings as well.

Thank you.

[insanePaPa]

Sec1 maths Question:

Two race cars, Car X and Car Y, are at the starting point of a 2km track at the same time. Car X and Car Y make one lap every 60s and 80s respectively.
How long, in minutes, will it take for the faster car to be 5 laps ahead of the slower car?

Thanks all Gurus in advance.

[ChiefKiasu]

insanePaPa:

Sec1 maths Question:

Two race cars, Car X and Car Y, are at the starting point of a 2km track at the same time. Car X and Car Y make one lap every 60s and 80s respectively.
How long, in minutes, will it take for the faster car to be 5 laps ahead of the slower car?

Thanks all Gurus in advance.

5 laps = 5 x 2km = 10km

Car A's speed = 2/60 = 1/30 kps
Car B's speed = 2/80 = 1/40 kps

Let T be time taken for Car A to be 10km ahead of Car B. Hence
(1/30)*T - (1/40)*T = 10
=> T(1/30 - 1/40) = 10
=> T(4-3/120) = 10
=> T(1/120) = 10
=> T = 1200s = 20mins