Question
Ravi and Sunil can complete a task in 12 days and 30
days respectively. Ravi started the task alone. After how many days should Sunil join him so that the task is completed in 10 days?Solution
ATQ,
Let the total work be 60 units (LCM of 12 and 30)
Efficiency of Ravi = 60 / 12 = 5 units/day
Efficiency of Sunil = 60 / 30 = 2 units/day
Let the time after which Sunil joined be n days.
So,
5n + (5 + 2) × (10 - n) = 60
5n + 70 - 7n = 60
-2n = -10
n = 5
In a purse, there are 3 two-rupee coins and 4 five-rupee coins. If you randomly select 4 coins from the purse, what is the probability that you will cho...
In how many ways can the letters of the word "COMPUTER" be arranged, and what is the probability that all the vowels in these arrangements always appear...
A black and a red dice are rolled. Find the conditional probability of obtaining a sum greater than 9, given that the black die resulted in a 5.
A company wants to pack 144 small boxes, 216 medium boxes, and 288 large boxes into cartons such that each carton contains the same number of boxes of e...
The probability that Leah will be accepted into program P is 60% and into program Q is 40%. Leah prefers program 'P' first, then 'Q', and finally 'R'. A...
A bag contains 10 black, 8 red and 12 yellow balls. Two balls are randomly drawn from the bag, what is the probability that a red and a yellow ball are ...
21 rotten bananas are accidentally mixed with 135 good ones. It is not possible to just look at a banana and tell whether or not it is rotten. One banan...
A bag contains cards which are numbered from 2 to 90. A card is drawn at random from the bag. Find the probability that the card number is a perfect squ...
- ‘A’ and ‘B’ play a game. A fair coin is tossed 4 times. ‘A’ wins if all tosses give different results alternately. What is the probability of �...
If 2 pens are drawn at random what is the probability that none of them is blue?
Relevant for Exams:
