Mani Raja

An insect colony doubles in population every 10 years. Its population is reduced by 20% every 7 years. After 50 years, the population of this colony is how many times its initial population, rounded to the nearest integer. How to solve this problem ?

Jane must select three different items for each dinner she will serve. The items are to be chosen from among five different vegetarian and four different meat selections. If at least one of the selections must be vegetarian, how many different dinners could Jane create? Atleast one vegetarian means one veg,two veg or 3 veg.So i solved as 1 veg=5*4*3, 2 veg=5*4*4, 3 veg=5*4*3,which gives the sum of 60+80+60=200.Where am i doing wrong ? please explain

Q- Joe will pick 3 friends to join him on a road trip.His friend group consist of 4 musicians and 3 poets.In how many different ways can joe select his 3 traveling companions so that he has atleast one musicians and atleast one poet among them ? A-Joe has two ways: “two musician and one poet” or “two poet and one musician”. I’m using slot method. For the 1st case 4*3*3 =36 and the 2nd case 3*2*4 =24.So,36+24=60 ways ? But the answer is wrong.Where am i going wrong ?

Hi all, If it takes 3 days for 10 workers to finish building a house,how many days will it take 15 workers to finish 4 houses ? How to solve these kind of problems ?

Q- Joe will pick 3 friends to join him on a road trip.His friend group consist of 4 musicians and 3 poets.In how many different ways can joe select his 3 traveling companions so that he has atleast one musicians and atleast one poet among them ? A-Joe has two ways: “two musician and one poet” or “two poet and one musician”. I’m using slot method. For the 1st case 4*3*3 =36 and the 2nd case 3*2*4 =24.So,36+24=60 ways ? But the answer is wrong.Where am i going wrong ?

Q- Joe will pick 3 friends to join him on a road trip.His friend group consist of 4 musicians and 3 poets.In how many different ways can joe select his 3 traveling companions so that he has atleast one musicians and atleast one poet among them ? A-Joe has two ways: “two musician and one poet” or “two poet and one musician”. I’m using slot method. For the 1st case 4*3*3 =36 and the 2nd case 3*2*4 =24.So,36+24=60 ways ? But the answer is wrong.Where am i going wrong ?

b,c and d are consecutive even integers such that 2 i can understand everything except how they got the fourth 2 in the prime factorisation. and also let b=4,c=6,d=8 then bcd will be 192. isn't 192 the largest divisor of 192 ?

Thanks a lot.

A mixture of 12 ounces of vinegar and oil is 40 percent vinegar,where all of the measurements are by weight.How many ounces of oil must be added to the mixture to produce a new mixture that is only 25 percent vinegar ? i often get confusion with these type of percents with mixture problem..is there any shortcut for this type of problem ?