Acupboard contains 20 boxes of chalks which are red and blue in colour. a box of chalks is chosen at random from the cupboard. if the probability of choosing a box of blue chalks is 1/4 ,calculate 1)the number of boxes of red chalks in the cupboard2) the number of boxes of blue chalks that should be put into the cupboard so that the probability of choosing a box of blue chalks is 2/5

Let say that there are boxes with red chulk, and boxes with blue chulk. The total is obviously boxes.

If the probability of choosing a box of blue chalks is , it means that

which implies

So, there are blue boxes and red boxes (remember that the total is ).

Now, suppose that we add new boxes with blue chulk. The number of blue boxes becomes , and the total number becomes . The new probability of having a blue box is if

Cross multiply the denominators:

Expand:

Bring all -like terms to the left and all constants to the right:

Simplify:

So, you should add more boxes of blue chulk.

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brainliest answers are handed out by the person asking the question, so whether your answer is picked depends entirely on whether the asker bothers to pick

if you're asking about your rank, it depends on having a certain number of points and a certain number of brainliest answers. for example, at the time of this writing, i have 44338 points out of 15000 needed for the next (nearly triple the requirement! ) but i only have 24 out of 50 required brainliest answers. this number decays, meaning after a certain amount of time (i think about a month), the total number of brainliest answers you've earned doesn't count toward this total. (i've been stuck at the same rank for a long

the lesson to learn here is that you shouldn't worry about points or rank. chances are, no matter how good an answer you may provide, your efforts will go mostly unnoticed unless you focus on the newest/most active questions that get posted.

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step-by-step explanation: