On marks last test the ratio of questions he answered correctly to questions he answered incorrectly weas 12: 7 if he answered 21 answers incorrectly how many questions were on the test?

In total, there were 57 questions on the test.

Step-by-step explanation:

Here, the number of  questions answers incorrectly =21

Let us assume the number of  questions answers correctly = m

So, the ratio of questions answered Correctly : Incorrectly = m : 21 ... (a)

Also, from the given question:

The ratio of questions he answered correctly to questions he answered incorrectly =   12:7   ..........  (b)

By the RATIO OF PROPORTION:

m : 21  = 12  : 7

or,

or, m = 36 ( app.)

So,  the number of questions answered correctly  = 36

Now, Total Q  = Q answered (Correctly + Incorrectly)

                       = 21 +  36  =  57

Hence in total, there were 57 questions on the test.

option 1 is correct.

step-by-step explanation:

y varies inversely with x and constant of variation is 4

the equation will be:

y = k/x

where k =4 so,

y = 4/x

if we put values of x of option 1 in the above equation and find values of y

y = 4/-2 => y =-2

y = 4/-1 => y = -4

y = 4/1 => y = 4

y = 4/2 => y =2

so, all the values of x and y are correct.

if we put values of x given in other options and find value of y we cannot find whole table satisfying the equation.

hence option 1 is correct.

probability for j is 1/4

while

a is 1/6