Originally posted by Lqq889:
1. Mrs wong has 2000 plants in her farm.
65% are orchids and rest are roses.
After some of the orchids are sold, and some of the
roses are added,
the percentage of the orchid become 45% of the total
plant.
if the number of the roses she added are 125, find how
many orchids do she sell?
2. Aron and Kurmar run a 24 km marathon.
Aron runs half the distance at 10 km/h, and jogs the
rest at 8 km/h.
Kurmar runs half of his total time at 12 km/h and
rest of time at 6 km/h.
if they start at 8 am, what time do they run finish
respectively?
1.) 65% of the plants are orchid, so 35% are roses.
Let x be the number of orchid sold.
At first
Number of orchid = 65% x 2000 = 1300
Number of roses =35% x 2000 = 700
Now
Number of orchid = 1300 - x
Number of roses = 700 + 125 = 825
Total = 1300 - x + 825 = 2125 - x
Since it is 45% of total plants,
Number of orchid / Total plants = 45 / 100
1300 - x / 2125 - x = 9 / 20
20(1300 - x) = 9(2125 - x)
26000 - 20x = 19125 - 9x
20x - 9x = 26000 - 19125
11x = 6875
x = 625
Hence, Mrs Wong sold 625 orchids.
2.) This is a trick question, so you will have to be careful about it.
The first part is about Aron, which is more direct.
Half the distance = 1/2 x 24km = 12km
Time taken for 1st half = 12/10 h = 1.2h = 1h 12mins
Time taken for 2nd half = 12/8 h = 1.5h = 1h 30mins
Total time Aron has taken = 1h 12mins + 1h 30mins = 2h 42mins
Time Aron finishes = 8am + 2h 42mins = 10.42am
The second part is about Kurmar, and many students will be tricked into thinking that half the total time and half the distance is the same. It is far from the same though.
Since he jogged 12km/h half the time and 6km/h half the time, on the average, he ran 18km/2h, which is the same as 9km/h.
Total time Kurmar has taken = 24/9 h = 2 and 2/3 h = 2h 40mins
Time Kurmar finishes = 8am + 2h 40mins = 10.40am