Tolong bggt bantu jawab makasihh tolong jangan ngawur

Tolong bggt bantu jawab makasihh tolong jangan ngawur

4, 5, 5, 5, 6, 6, 7, 7, 8, 8, 9, a

rata-rata = jumlah semua data / banyak data

$6.5 = frac{4 + (3 times 5) +(2 times 6) + (2 times 7) + (2 times 8) + 9 + a}{12} \ frac{13}{2} = frac{4 + 1 5+ 12 + 14 + 16 + 9 + a}{12} \ frac{13}{2} = frac{70 + a}{12} \ 70 + a = frac{13}{2} times 12 \ 70 + a = 13 times 6 \ 70 + a = 78 \ a = 78 - 70 \ a = 8$