A real estate broker has 11 unsold houses in Gulmarg colony, Broker planned to sold 4 houses to a perspective buyer. In how many ways can Broker plans to sell houses such that no two of them are next to each other?

A real estate broker has 11 unsold houses in Gulmarg colony, Broker planned to sold 4 houses to a perspective buyer. In how many ways can Broker plans to sell houses such that no two of them are next to each other? Correct Answer 70

GIVEN:

Total Houses = 11

Sold houses = 4

CALCULATIONS:

Initially, let's remove the 4 houses which are going to be sold.

Then we are left with 11 − 4 = 7 houses as numbered below.

_ 1 _ 2 _ 3 _ 4 _ 5 _ 6 _ 7_

Now there are 8 positions as marked as “_ " to place the 4 houses (which the broker sells) among 7 houses such that no two such houses are next to each other.

Number of ways to place 4 houses so that no two are next to each other = 8C4 ways.

⇒ Required number of ways = 8C4 = (8 × 7 × 6 × 5) / (4 × 3 × 2 × 1) = 70

∴ Required number of ways is 70.

Related Questions

What was the average weight of all the persons in the colony? Statement I: There are total 40 persons in the colony. Statement II: If 3 persons whose average weight is 56.5 kg left the colony and 3 new persons whose total weight is 137.5 kg joined the colony then the average weight of all the persons in the colony decreases by 0.8 kg. 
Read the passage carefully and choose the best answer to each question out of the four alternatives and click the button corresponding to it.
Fever in the season of dengue is sending Calcuttans scurrying to hospitals for admission, triggering a shortage of beds that has forced some private health care institutes to even postpone planned surgeries. Apollo Gleneagles Hospitals on the Bypass had 504 patients in its care as on Thursday of whom 70 had been admitted with fever. Belle Vue Clinic had 180 patients, 32 of them with dengue. Calcutta Medical Research Institute had 350 patients 60 of them with fever. The number of people admitted for treatment of fever caused by dengue or any undiagnosed illness has been rising every day across hospitals for more than a fortnight. "There has been heavy pressure on all private hospitals for admission of dengue and cases of unknown fever since the beginning of August. Now it is a surge," said Pradip Tondon, President of the Association of Hospitals of Eastern India. In July, four to five patients were getting admitted with fever on an average in every hospital. The number has since ballooned with the Calcutta Municipal Corporation apparently in denial about the extent of the dengue outbreak and the Government focused on playing down the threat. Such has been the rush of patients with fever that some hospitals are calling up people to postpone admissions planned in advance, mostly for surgeries. "We have told many people to come only when we call them to confirm availability of beds," said an official at Belle Vue.
The rush in hospitals has been rising
Read the passage carefully and choose the best answer to each question out of the four alternatives and click the button corresponding to it.
Fever in the season of dengue is sending Calcuttans scurrying to hospitals for admission, triggering a shortage of beds that has forced some private health care institutes to even postpone planned surgeries. Apollo Gleneagles Hospitals on the Bypass had 504 patients in its care as on Thursday of whom 70 had been admitted with fever. Belle Vue Clinic had 180 patients, 32 of them with dengue. Calcutta Medical Research Institute had 350 patients 60 of them with fever. The number of people admitted for treatment of fever caused by dengue or any undiagnosed illness has been rising every day across hospitals for more than a fortnight. "There has been heavy pressure on all private hospitals for admission of dengue and cases of unknown fever since the beginning of August. Now it is a surge," said Pradip Tondon, President of the Association of Hospitals of Eastern India. In July, four to five patients were getting admitted with fever on an average in every hospital. The number has since ballooned with the Calcutta Municipal Corporation apparently in denial about the extent of the dengue outbreak and the Government focused on playing down the threat. Such has been the rush of patients with fever that some hospitals are calling up people to postpone admissions planned in advance, mostly for surgeries. "We have told many people to come only when we call them to confirm availability of beds," said an official at Belle Vue.
The Government's "playing down the threat" means