Bobby had 36 books in his locker. some were library books, some were textbooks, and the rest were telephone books. the number of library books and telephone books combined equals twice the number of textbooks. the number of textbooks and telephone books combined equals three times the number of library books. how many of each type of book were in bobby's locker?

Let x be the libaray books, y be the textbooks and z be the telephone books

x + y + z = 36 ...(1)

x + z = 2y

y =

y + z = 3x ...(3)

Plugging eq 2 into 1 and 3

x +

3x + 3z = 72 ...(4)

x + 3z = 6x

3z - 5x = 0 ...(5)

Subtract eq(4) from 5 and simplfy:

3x - (- 5x) = 72

3x + 5x = 72

8x = 72

x = 9

And, 3z = 5x

3z = 5(9)

z = 15

And, y =

y = 12

Hence, there are 9 libaray books, 12 textbooks and 15 telephone books in the locker.

85.560%

step-by-step explanation:

conditional probability is defined as:

p(a|b) = p(a∩b) / p(b)

in other words, the probability that a occurs, given that b has occurred = the probability that both a and b occur / the probability that b occurs.

in this example:

p(turns 64 | turns 44) = p(turns 64 & turns 44) / p(turns 44).

if someone turns 64, they must have already turned 44, so:

p(turns 64 | turns 44) = p(turns 64) / p(turns 44)

on page 42, we see that of the original 100,000, 94944 turn 44, and 81234 turn 64.   therefore:

p(turns 64 | turns 44) = 81234 / 94944

p(turns 64 | turns 44) = 0.85560