Advertisements
Advertisements
Question
The variable x varies directly as y and x = 80 when y is 160. What is y when x is 64?
Advertisements
Solution
If x varies directly as y.
∴ `x/y = k` (constant) ...(i)
If x = 80 and y = 160
∴ `x/y = 80/160 = 1/2`
⇒ `k = 1/2`
When x = 64, then from equation (i),
`64/y = 1/2` ...[Putting the value of k]
⇒ y = 64 × 2 = 128
APPEARS IN
RELATED QUESTIONS
In a model of a ship, the mast is 9 cm high, while the mast of the actual ship is 12 m high. If the length of the ship is 28 m, how long is the model ship?
Sita can finish typing a 100 page document in 9 hours. Mita in 6 hours and Rita in 12 hours. How long will they take to type a 100 page document if they work together?
A and B can do a piece of work in 12 days; B and C in 15 days; C and A in 20 days. How much time will A alone take to finish the work?
For 9 cows, 13 kg 500 g of food supplements are required every day. In the same proportion, how much will be needed for 12 cows?
Both x and y are in direct proportion, then `1/x` and `1/y` are ______.
Devangi travels 50 m distance in 75 steps, then the distance travelled in 375 steps is ______ km.
When the distance is kept fixed, speed and time vary directly with each other.
If 25 metres of cloth costs Rs 337.50, then what will be the length of the cloth bought for Rs 810?
Ravi starts for his school at 8:20 a.m. on his bicycle. If he travels at a speed of 10 km/h, then he reaches his school late by 8 minutes but on travelling at 16 km/h he reaches the school 10 minutes early. At what time does the school start?
Many schools have a recommended students-teacher ratio as 35:1. Next year, school expects an increase in enrolment by 280 students. How many new teachers will they have to appoint to maintain the students-teacher ratio?
