To make one cheese sandwich, Tina uses one bread roll and two cheese slices. Pack of 15 bread rolls £1.91 . Pack of 20 cheese slices £2.23 . She is going to buy enough packs to have exactly twice as many cheese slices as bread rolls. Make more than 100 cheese sandwiches. Work out the least amount she can spend.

Rachel is studying the population of a particular bird species in a national park. she observes every 10th bird of that species that she can find in the park. her conclusion is that the birds living in the park who belong to that species generally feed on insects. rachel's sample is . based on the sample she picked, rachel's generalization is