Help ...probabilty/??

Help ...probabilty/??

1.find the probability of getting a total score of 4 when john throws two fair dice together.

If the die are thrown 100 times, estimate the expected number of times john will get a score of 4

2. A dice is made so that the probability of getting a 6 is 3/10, and the probability of getting a 5 is 2/10. The probabilites of gettin any other number are all equal. If the dice is thrown twice, find the probability

i) you get 2 sixes

ii)you get no sixes

iii)the sum of 2 numbers is 6

Please show working out, these were two of 15 questions I couldnt do.

Thanks

Relevance
• Jacob
Lv 5

Probability of getting total 4

2 and 2 chance= 1/6 x 1/6

=1/36

Or 3 and 1 being thrown

= 1/6 x 1/6

= 1/36

Chance of either happening is 1/36 + 1/36 = 1/18

So chance of getting a total score of 4 = 1/18

100/18 = 5.5 round up to 6

100 throws = 6 scores of 4 (i think)

2.

i. 2 sixes = 3/10 x 3/10 = 9/100

ii. no sixes = 7/10 x 7/10 = 49/100

iii. sum of 2 throws is 6

1/10 x 1/10 for getting two 3s (1/100

(1/10 x 1/10)x2 for getting 4 & 2 (1/50)

(2/10 x 1/10)x2 for getting 5 & 1 (1/25)

Add all the above = 7/100