Question
The average of 18 numbers is 75.
The average of the first nine numbers and the last six numbers is 62.5 and 82.5, respectively. The 12th number is 34.3 more than 1.8 times the 10th number, which itself is 119.5 less than the 11th number. What is the value of the 11th number?Solution
ATQ,
Let 10th number is βxβ So, 12th number = 1.8 Γ x + 34.3 And, 11th number = x + 119.5 So, x + 1.8x + 34.3 + x + 119.5 = 18 Γ 75 β 9 Γ 62.5 β 6 Γ 82.5 = 292.5 Or, 3.8x = 138.7 Or, x = 36.5 So, 11th number = 36.5 + 119.5 = 156
A biker travels at a speed of 32 km/hr for 6 hours each day on all days except Sunday. If his journey starts on a Wednesday, on which day will he reach ...
The speed of current is 10 km/h. What will be the respective downstream speed and upstream speed of a boy rowing a boat, if one sixth of the distance co...
- In a 200-metre race, runner A can give runner B a 20-metre head start and still finish at the same time. Similarly, runner B can give runner C a 10-metre h...
A motor car starts with a speed of 60 km/h and increases its speed after every two hours by 15 km/h. In how much time will it cover a distance of 360 km?
Sheetal rides a bike at an average speed of 40 kmph and reaches her destination in 5 hours. Hemlata covers the same distance in 4 hrs. If Sheetal increa...
A school bus arrives at the school on time when it maintains an average speed of 50 km/h. However, if the bus travels at an average speed of 40 km/h, it...
βAβ and βBβ started moving towards each other at same time with a speed of 25 km/hr and 15 km/hr, respectively. If the distance covered by βAοΏ½...
The two places are 60 km apart. A and B start walking towards each other at the same time and meet each other after 6 hours. Had A traveled with 2/3rd o...
A was travelling from point X to point Y. He increased his speed by 18 km/h after every hour. He reached his destination in 20 hours. If his initial spe...
- A car travels from city βAβ to city βBβ covering (1/3)rd of the total distance in 5 hours and the rest in 7 hours. If it takes 8 hours to return to...
