If Rati travels at his usual speed for ‘x’ hours, he covers the same distance as he covered when he travels at a speed 30 km/hr less than usual, but for (x + 3) hours. Which of the following can be determined? (A) If he travels at 20 km/hr less speed than usual, he can cover a distance of 240 km in (x - 1) hours. What is the value of ‘x’? (B) If travels at his usual speed for (t + 2) hours, and at 50% of his usual speed for (t - 2) hours, his average speed for the journey is 68 km/hr. What is his usual speed? (C) His usual speed (in km/hr) is a multiple of 5 between 40 and 50 (both inclusive). If ‘x’ is a whole number, what is his usual speed? (D) If he travels at his usual speed for ‘t’ hours, he covers a distance of 400 km. What is the value of ‘x’?

If Rati travels at his usual speed for ‘x’ hours, he covers the same distance as he covered when he travels at a speed 30 km/hr less than usual, but for (x + 3) hours. Which of the following can be determined? (A) If he travels at 20 km/hr less speed than usual, he can cover a distance of 240 km in (x - 1) hours. What is the value of ‘x’? (B) If travels at his usual speed for (t + 2) hours, and at 50% of his usual speed for (t - 2) hours, his average speed for the journey is 68 km/hr. What is his usual speed? (C) His usual speed (in km/hr) is a multiple of 5 between 40 and 50 (both inclusive). If ‘x’ is a whole number, what is his usual speed? (D) If he travels at his usual speed for ‘t’ hours, he covers a distance of 400 km. What is the value of ‘x’? Correct Answer Only A, B and D

Let the usual speed of Rati be ‘x’ km/hr

So, x × t = (x – 30) × (t + 3)

xt = xt + 3x – 30t – 90

x – 10t = 3      ----(i)

(A) : Now, (x – 20) (t – 1) = 240

xt – x – 20t + 20 = 240

xt – x – 20t = 220

(10t + 30) × t – (10t + 30) – 20t = 220

10t2 + 30t – 10t – 30 – 20t = 220

10t2 = 250

T = 5

So, the value of ‘t’ is determined.

(B) : So, total distance travelled = x(t + 2) + (x/2) × (t – 2) = (3xt/2 + x) km

Total time taken = (t + 2) + (t – 2) = 2t

So, (3xt/2 + x)/2t = 68

3t(10t + 30)/2 + (10t + 30) = 136t

15t2 + 45t + 10t + 30 = 136t

15t2 – 81t + 30 = 0

5t2 – 27t + 10 = 0

(5t – 2) (t – 5) = 0

So, t = 2/5 or 5 but t = 2/5 is not possible

For t = 5, x = 80

So, the value of ‘x’ can be determine.

(C) : Multiples of 5 between 40 and 50 are 40, 45 and 50

For x = 40, t = 1

For x = 45, t = 1.5

For x = 50, t = 2

Since, ‘t’ is a whole number, t = 1 or 2

So, the value of ‘x’ cannot be determined.

(D) : So, xt = 400

T = 400/x

Putting in (i)

x – 400/x = 30

x2 – 30x – 400 = 0

(x – 40) (x + 10) = 0

x = 40

So, the value of ‘x’ is determined.

Related Questions

Each of the question below consists of a question and three statements number I, II and III given below it. You have to decide whether the data provided in the statement are sufficient to answer the question. If the bus is travelling from Surat to Ahmadabad and a car is travelling from Ahmadabad to Surat, then what is the distance between Surat and Ahmadabad? I. The speed of a car is 40% less than the speed of bus. Bus started at 9 am and car started at 10 am and they meet at 3 pm of the same day. II. After travelling for 1 hour, because of traffic average speed of bus is decreased by 20% and covers distance between Surat to Ahmadabad in 11 hours. Original speed of car is 20% less than original speed of bus and before crossing bus it covered 200 km if starts 1 hour later than bus. After crossing car, bus covers remaining distance in 5 hours. III. Speed of bus is 10 km/hr more than the speed of car and before crossing car ratio of distances covered bus and car in same time was 5 : 4. Time taken by car to cover the distance between Ahmadabad and Surat is 2 hours 15 minutes more than time taken by bus to cover the same distance.