What are the 4 different ratios of 48:16

When you have 25 numbers, and jake picks 3 random numbers and puts them back, what is the chance bob has of picking those 3 numbers when he picks 6 random numbers (without putting them back)? explain.

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years

Julie buys 2kg of apples and 7kg of pears ? 12.70. the pears cost ? 1.30 per kilogram what is the price per kilogram of the apples? show your working out