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A b uilding c onta ins 22 room s in to tal. 9 of the room is are on the g roun d floo r. 7 of the rooms have blue wa IIS. 4 of th e roo ms th at ar e on the grou nd floor also have blue w alls. Work out the pro babili ty tha t a ro om picked at ra ndom is ne ither on the grou nd flo or nor has blue walls. Give yo ur an swer as a fr acti on in it s simple st fo rm.

Question

A b uilding c onta ins 22 room s in to tal.
9 of the room is are on the g roun d floo r.
7 of the rooms have blue wa IIS.
4 of th e roo ms th at ar e on the grou nd
floor also have blue w alls.
Work out the pro babili ty tha t a ro om
picked at ra ndom is ne ither on the
grou nd flo or nor has blue walls.
Give yo ur an swer as a fr acti on in it s
simple st fo rm.

A b uilding c onta ins 22 room s in to tal. 9 of the room is are on the g roun d floo r. 7 of the rooms have blue wa IIS. 4 of th e roo ms th at ar e on the grou nd floor also have blue w alls. Work out the pro babili ty tha t a ro om picked at ra ndom is ne ither on the grou nd flo or nor has blue walls. Give yo ur an swer as a fr acti on in it s simple st fo rm.

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LucasElite · Tutor for 8 years

Answer

<p> 6/11</p>

Explain

<p> To calculate the probability of an event, the general method is to divide the number of ways an event can occur by the total number of possible outcomes.<br /><br />In this scenario, the total number of rooms is 22. The number of ground-floor rooms is 9, and among these 9, 4 also have blue walls. The total number of rooms with blue walls is 7, whether they're on the ground floor or not.<br /><br />From here, we can calculate the number of rooms that are either on the ground-floor or have blue walls or both. This can be given by : number of ground-floor rooms + number of rooms with blue walls - number of rooms that are both on the ground floor and have blue walls.<br /><br />To get the number of rooms that are neither on the ground floor, nor are painted blue, we subtract these from the total number of rooms.<br /><br />The requested probability is then found as the fraction: (rooms that are neither on the ground floor nor blue) / (total rooms), and simplified to its lowest terms.</p>
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