To make a magic potion, Harry Potter needs five kinds of herbs: liquorice (cam thảo), pseudoginseng (tam thất), artichoke (ác-ti-sô), ming aralia (đinh lăng) and bitter melon (mướp đắng). Each amount must be weighed exactly using the balances shown. He needs 7 grams of artichoke. Treat the weights of the balances as negligible.
Using the picture, how many grams does he need of each of the following?
– Ming aralia
– Bitter melon
– Pseudoginseng
– Liquorice
Violet has the nine numbers 1,2,3,4,5,6,7,8 and 9. She adds some of them to 2 and adds all the remaining numbers to 3. What is the smallest possible difference between the two sums?
Ann, Bin and Joly have 30 sweets altogether. Ann has fewer than Bin, and Bin has fewer than Joly. If Joly gives Ann 2 sweets, Joly has fewer than Bin and Bin has fewer than Ann. How many sweets does Bin have?
Posts stand at A,B,C and D. Tom wants to join 3 posts with 3 straight fences so that as many kangaroos as possible are inside. What is the greatest number of kangaroos that can be enclosed?
Plane, Train and Ship race to see who finishes first. Plane finishes before Ship. Train finishes before Ship. But Plane does not finish first. Who wins?