There are 56 marbles in a tank. The probability of drawing a red marble at random from the tank is 5/8
a) Find the number of marbles in the tank that are not red.
b) The rest of the marbles are either blue or yellow. When two marbles are drawn with replacement, the probability of drawing 1 blue marble and 1 red marble is 5/16. Find the number of yellow marbles in the tank.
I have already found the number of marbles in the tank that are not red = 21 (correct)
Answer for b is 7, just need the steps. Thank you.
Question is from Mathematics in Action @Pearson Chapter 20 Question 24
Form 5 Probability Question
2015-07-24 10:07 pm
回答 (2)
2015-08-03 10:13 pm
無最佳解答
2015-07-24 10:32 pm
a)
The number of marbles in the tank that are not red
= ( 56 ) ( 1 - 5/8 )
= 21
b)
Let x be the number of blue marbles
[ ( 56 - 21 ) / 56 ] ( x / 56 ) + ( x / 56 ) [ ( 56 - 21 ) / 56 ] = 5 / 16
藍色指第一次攞到 Blue，第二次攞到 Red
紅色指第一次攞到 Red，第二次攞到 Blue
( 35x / 3136 ) ( 2 ) = 5 / 16
35x = 490
x = 14
∴The number of yellow marbles
= 21 - 14
= 7
The number of marbles in the tank that are not red
= ( 56 ) ( 1 - 5/8 )
= 21
b)
Let x be the number of blue marbles
[ ( 56 - 21 ) / 56 ] ( x / 56 ) + ( x / 56 ) [ ( 56 - 21 ) / 56 ] = 5 / 16
藍色指第一次攞到 Blue，第二次攞到 Red
紅色指第一次攞到 Red，第二次攞到 Blue
( 35x / 3136 ) ( 2 ) = 5 / 16
35x = 490
x = 14
∴The number of yellow marbles
= 21 - 14
= 7
收錄日期: 2021-04-16 17:06:25
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