Basil asks each of 40 students how many books they bought last year. Can anyone answer B?

10 books.

Step-by-step explanation:

(b) To estimate the mean we take the mean value of books for each bar.

So for 0-4 books we use 4/2 = 2, for 5-9 we use (9-5)/ 2 + 5 = 7 and so on for each bar.  So the estimate for the first bar is 2 * 9 = 18 books.

So the required mean = total estimate of books bought / number of students

= (9 *2 + 10*7 + 12*13 + 17*2 + 22*6) / 40

= 410 / 40

= 10.25

at home andrea has 1 2/3 kilograms of rice

step-by-step explanation:

51

step-by-step explanation:

73-22=51 the   mass number minus the amount of protons gives you the amount of neutrons