There are 13 members in a committee having 7 men and 6 women. In how many ways a team of 4 persons can be selected in such a way that at least 1 men would be there in the team.
Number of ways with 1 men = 7/1 * 6*5*4/3*2*1 = 140
Number of ways with 2 men = 7*6/2*1 * 6*5/2*1 = 315
Number of ways with 3 men = 7*6*5/3*2*1 * 6/1 = 210
Number of ways with 4 men = 7*6*5*4/4*3*2*1 = 35
Total number of ways = 700
For x = 1, y and z can be arranged in 7 ways
for x = 2, y and z can be arranged in 6 ways
for x = 3, y and z can be arranged in 5 ways
Similarly
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for x = 7, y and z can be arranged in 1 ways
Total ways = 7+6+5+4+3+2+1 = 28
So probability 1/28
Option 1)
The rate of interest on a sum of money is 4% per annum for the first 2 years, 6% per annum for the next 4 years and 8% per annum for the period beyond 6 years. If the simple interest accrued by the sum for a total period of 9 years is Rs. 1120, what is the sum?
Time taken by 9 men to finish the whole work = 30 days
Remaining work = (1 - 1/3) = 2/3
More work, more men (direct)
Less days, more men (indirect)
Work 1/3 : 2/3
Days 2 : 10
:: } 9:x
Therefore x = (2/3 * 10 * 9 * 3 * 1/2) = 90
Hence, additional number of men = 90-9 = 81
Option 1)
If 5 engines consume 6 metric tonnes of coal when each is running 9 hours a day, how much coal (in metric tonnes) will be needed for 8 engines, each running 10 hours a day, it being given that 3 engines of the former type consume as much as 4 engines of latter type?
More engines, more coal (Direct)
More hours a day, more coal (Direct)
More rate of consumption, more coal (Direct)
Engines ------------ 5:8
Hrs/day ------------ 9:10
Rae of consumption - (1/3):(1/4)
6:x
Therefore
x = (8*10*(1/4)*6*(1/5)*(1/9)*3) = 8 metric tonnes.
Option 10)