Debbie giữ bộ sưu tập đá cẩm thạch của cô trong một cái bình. Trong số 50 viên bi trong bình, 15 màu đỏ, 10 màu xanh, 20 là màu xanh lá cây và 5 là màu vàng. Debbie chọn ngẫu nhiên 30 viên bi từ jar. Bao nhiêu trong số các viên bi cô có thể mong đợi để có màu đỏ? 
Trả lời: ... hòn bi

Bản gốc : Debbie keeps her marble collection in a jar. Of the 50 marbles in the jar, 15 are red, 10 are blue, 20 are green and 5 are yellow. Debbie chooses randomly 30 marbles from the jar. How many of these marbles can she expect to be red?
Answer: ... marbles

Exam number 1: Đi tìm kho báu

Question 1: There are 40 students in Mrs. Brown's class. 25% of her students received a B on the test. How many students received a B?

a. 10                   b. 12                     c. 18                  d. 20

Question 2: What is the product of 3.05 and 2.8?

a. 8.54                  b. 8.056                 c. 8.56               d. 8.054

Question 3: A clothing shop is having a 40% off sale. How much would Jane have to pay for a $30 sweater with a 40% discount?

a. $18                  b. $20                   c. $50                d. $13

Question 4: If a pen costs $1.75 and an eraser costs $0.85, which of the following is the cost of 10 erasers and 5 pens?

a. $21.75                b. $26                  c. $18.75             d. $17.25

Question 5: If the area of the rectangle ABCD is 60cm² then the area of the trapezoid MNCD is ..........cm².

a. 48                    b. 50                  c. 45                  d. 54

Exam number 2: Tìm cặp bằng nhau

Exam number 3: Fill in the blank with the suitable number

Question 1 The length of each edge of a cube is 3 cm. The surface area of the cube, in cm2, is .............

Question 2: At the beginning of the summer, Bob was 140 cm tall. At the end of the summer, he measured his height again and discovered that it had increased by 5%. Measured in cm, what was his height at the end of summer?

Question 3: The number of centimetres in 7.05 metres is ...............

Question 4: Bella scores on six of her eight pictures. The percentage of pictures that she does not score on is .........%.

Question 5: A bag contains green marbles and red marbles only. If the ratio of the number of green marbles to the number of red marbles is 1:4 then ............% of marbles are green.

Question 6: How many even numbers between 1 and 100 are divisible by 5?

Question 7: Alice is going to the store. One third of the way to the store, she stops to talk with Kelly. She then continues for 6 km and reaches the store. How many kilometres does she travel?

Question 8: How many three-digit numbers are exactly 19 more than a two-digit number?

Question 9: In the 3×3 table shown, the numbers 2, 4 and 6 are placed so that each number occurs only once in each row and only once in each column. The value of M + N is ............

Question 10: How many different 3-digit whole numbers can be formed using the digits 4, 5, 0 and 8, assuming that no digit can be repeated in a number?