快猫短视频

#112 A muse in the barrel

Solution

The third barrel has a diameter of 180 cm. The angle between the ground and the line passing through the centre of the barrels is 30 degrees, so in the dotted triangle, the height divided by the hypotenuse = 陆. The smallest barrel鈥檚 radius is 10 cm, so if the second barrel has radius a and the third b, a/(a+30) = 陆, so a = 30, and b/(b+90) = 陆, so b = 90 and the third barrel鈥檚 diameter is 180 cm.

#113 The two-ewes day paradox

Farmer Giles is thrilled that his rare-breed sheep, Lewecy, is pregnant with twins. He has hired an expert from the genetics clinic to find out more about the lambs-to-be.

The clinic has a reliable prenatal test that looks for fragments of fetal Y chromosome circulating in Lewecy鈥檚 blood.

The test has come up positive, which means that at least one of the lambs will be male.

鈥淚鈥檓 pleased that there鈥檒l be another ram on the farm,鈥� thinks Giles, 鈥渂ut I do hope the second lamb will be female so that I鈥檒l have two ewes on the farm next year. There鈥檚 roughly a 50-50 split between male and female lambs, so if one鈥檚 a male then it鈥檚 odds-on that the other lamb will be female.鈥�

Is Giles right to be optimistic?

Answer next week

Quick quiz #101

1 The splitting of a spectral line due to the presence of an electric field is known as what?

2 Which two toad species are native to the UK?

3 Whose observations of the radial velocities of spiral galaxies provided the first empirical evidence that our universe is expanding?

4 Where would you find Alexander鈥檚 band?

5 How many stages are there in Guedel鈥檚 classification, a means of assessing the depth of general anaesthesia?