Question
A box contains 6 red, 4 blue, 2 green and 4 yellow pens.
If four pens are picked at random, what is the probability that one is green, two are blue and one is red?Solution
Total number of pens = 6 + 4 + 2 + 4 = 16 Let S be the sample space. Then, n(S) = number of ways of drawing 4 pens out of 16 = ¹⁶C4 = (16 × 15× 14 × 13 )/( 4 × 3 × 2 × 1) = 1820 Let E= event of drawing 4 pens so that one is green, two are blue and one is red = n(E) = ²C1×⁴C2×⁶C1= 2 × 6 × 6= 72 ∴ P (E) = (n(E))/(n(S))= 72/1820 = 18/455
In a mayoral election between two nominees, 20% of the total votes were rejected as invalid. Out of the valid votes, 65% went to the winning candidate, ...
Monthly income of A is Rs. 55000 out of which he spent 21%, 9% and 22% of his total income in rent, medicine and transportation, respectively. Find his ...
If the population of a city increases by 20% every year and is expected to be 43,200 after 2 years, then what is its present population?
A person 'P' allocates 25% of his monthly salary towards rent. Out of the remaining salary, he spends 40% on food and clothing, saving the rest. His tot...
The population of a village two years ago was 'X'. Over the next two years, the population increased by 30% in the first year and...
Income of A is twice the income of B. B and A spend 65% and 75% respectively of their incomes. Find the savings of A, if B saves Rs. 7000 in a month.
A person saves 30% of his monthly income. If his monthly is increased by 45% and he still saves the same amount as before then find percentage increase ...
A number is first increased by 55%, and then decreased by 35%. What is the net percentage change in the original number?
If 45% of a number is 90, what is 60% of the same number?
In village P, the number of male voters is 45% more than the number of female voters. The ratio of male voters in village P to village Q is 8:5. If the ...
Relevant for Exams:
